initial sabre upgrade (needs lots of work - to wit: authentication, redo the browser interface, and rework event export/import)

100 files changed, 15772 insertions, 5181 deletions

diff --git a/vendor/sabre/vobject/lib/BirthdayCalendarGenerator.php b/vendor/sabre/vobject/lib/BirthdayCalendarGenerator.php
new file mode 100644
index 000000000..afa41ab1c
--- /dev/null
+++ b/vendor/sabre/vobject/lib/BirthdayCalendarGenerator.php
@@ -0,0 +1,191 @@
+<?php
+
+namespace Sabre\VObject;
+
+use Sabre\VObject\Component\VCalendar;
+
+/**
+ * This class generates birthday calendars.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Dominik Tobschall (http://tobschall.de/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class BirthdayCalendarGenerator {
+
+    /**
+     * Input objects.
+     *
+     * @var array
+     */
+    protected $objects = [];
+
+    /**
+     * Default year.
+     * Used for dates without a year.
+     */
+    const DEFAULT_YEAR = 2000;
+
+    /**
+     * Output format for the SUMMARY.
+     *
+     * @var string
+     */
+    protected $format = '%1$s\'s Birthday';
+
+    /**
+     * Creates the generator.
+     *
+     * Check the setTimeRange and setObjects methods for details about the
+     * arguments.
+     *
+     * @param mixed $objects
+     */
+    function __construct($objects = null) {
+
+        if ($objects) {
+            $this->setObjects($objects);
+        }
+
+    }
+
+    /**
+     * Sets the input objects.
+     *
+     * You must either supply a vCard as a string or as a Component/VCard object.
+     * It's also possible to supply an array of strings or objects.
+     *
+     * @param mixed $objects
+     *
+     * @return void
+     */
+    function setObjects($objects) {
+
+        if (!is_array($objects)) {
+            $objects = [$objects];
+        }
+
+        $this->objects = [];
+        foreach ($objects as $object) {
+
+            if (is_string($object)) {
+
+                $vObj = Reader::read($object);
+                if (!$vObj instanceof Component\VCard) {
+                    throw new \InvalidArgumentException('String could not be parsed as \\Sabre\\VObject\\Component\\VCard by setObjects');
+                }
+
+                $this->objects[] = $vObj;
+
+            } elseif ($object instanceof Component\VCard) {
+
+                $this->objects[] = $object;
+
+            } else {
+
+                throw new \InvalidArgumentException('You can only pass strings or \\Sabre\\VObject\\Component\\VCard arguments to setObjects');
+
+            }
+
+        }
+
+    }
+
+    /**
+     * Sets the output format for the SUMMARY
+     *
+     * @param string $format
+     *
+     * @return void
+     */
+    function setFormat($format) {
+
+        $this->format = $format;
+
+    }
+
+    /**
+     * Parses the input data and returns a VCALENDAR.
+     *
+     * @return Component/VCalendar
+     */
+    function getResult() {
+
+        $calendar = new VCalendar();
+
+        foreach ($this->objects as $object) {
+
+            // Skip if there is no BDAY property.
+            if (!$object->select('BDAY')) {
+                continue;
+            }
+
+            // We've seen clients (ez-vcard) putting "BDAY:" properties
+            // without a value into vCards. If we come across those, we'll
+            // skip them.
+            if (empty($object->BDAY->getValue())) {
+                continue;
+            }
+
+            // We're always converting to vCard 4.0 so we can rely on the
+            // VCardConverter handling the X-APPLE-OMIT-YEAR property for us.
+            $object = $object->convert(Document::VCARD40);
+
+            // Skip if the card has no FN property.
+            if (!isset($object->FN)) {
+                continue;
+            }
+
+            // Skip if the BDAY property is not of the right type.
+            if (!$object->BDAY instanceof Property\VCard\DateAndOrTime) {
+                continue;
+            }
+
+            // Skip if we can't parse the BDAY value.
+            try {
+                $dateParts = DateTimeParser::parseVCardDateTime($object->BDAY->getValue());
+            } catch (InvalidDataException $e) {
+                continue;
+            }
+
+            // Set a year if it's not set.
+            $unknownYear = false;
+
+            if (!$dateParts['year']) {
+                $object->BDAY = self::DEFAULT_YEAR . '-' . $dateParts['month'] . '-' . $dateParts['date'];
+
+                $unknownYear = true;
+            }
+
+            // Create event.
+            $event = $calendar->add('VEVENT', [
+                'SUMMARY'      => sprintf($this->format, $object->FN->getValue()),
+                'DTSTART'      => new \DateTime($object->BDAY->getValue()),
+                'RRULE'        => 'FREQ=YEARLY',
+                'TRANSP'       => 'TRANSPARENT',
+            ]);
+
+            // add VALUE=date
+            $event->DTSTART['VALUE'] = 'DATE';
+
+            // Add X-SABRE-BDAY property.
+            if ($unknownYear) {
+                $event->add('X-SABRE-BDAY', 'BDAY', [
+                    'X-SABRE-VCARD-UID' => $object->UID->getValue(),
+                    'X-SABRE-VCARD-FN'  => $object->FN->getValue(),
+                    'X-SABRE-OMIT-YEAR' => self::DEFAULT_YEAR,
+                ]);
+            } else {
+                $event->add('X-SABRE-BDAY', 'BDAY', [
+                    'X-SABRE-VCARD-UID' => $object->UID->getValue(),
+                    'X-SABRE-VCARD-FN'  => $object->FN->getValue(),
+                ]);
+            }
+
+        }
+
+        return $calendar;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Cli.php b/vendor/sabre/vobject/lib/Cli.php
new file mode 100644
index 000000000..df7ac22f3
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Cli.php
@@ -0,0 +1,771 @@
+<?php
+
+namespace Sabre\VObject;
+
+use
+    InvalidArgumentException;
+
+/**
+ * This is the CLI interface for sabre-vobject.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Cli {
+
+    /**
+     * No output.
+     *
+     * @var bool
+     */
+    protected $quiet = false;
+
+    /**
+     * Help display.
+     *
+     * @var bool
+     */
+    protected $showHelp = false;
+
+    /**
+     * Wether to spit out 'mimedir' or 'json' format.
+     *
+     * @var string
+     */
+    protected $format;
+
+    /**
+     * JSON pretty print.
+     *
+     * @var bool
+     */
+    protected $pretty;
+
+    /**
+     * Source file.
+     *
+     * @var string
+     */
+    protected $inputPath;
+
+    /**
+     * Destination file.
+     *
+     * @var string
+     */
+    protected $outputPath;
+
+    /**
+     * output stream.
+     *
+     * @var resource
+     */
+    protected $stdout;
+
+    /**
+     * stdin.
+     *
+     * @var resource
+     */
+    protected $stdin;
+
+    /**
+     * stderr.
+     *
+     * @var resource
+     */
+    protected $stderr;
+
+    /**
+     * Input format (one of json or mimedir).
+     *
+     * @var string
+     */
+    protected $inputFormat;
+
+    /**
+     * Makes the parser less strict.
+     *
+     * @var bool
+     */
+    protected $forgiving = false;
+
+    /**
+     * Main function.
+     *
+     * @return int
+     */
+    function main(array $argv) {
+
+        // @codeCoverageIgnoreStart
+        // We cannot easily test this, so we'll skip it. Pretty basic anyway.
+
+        if (!$this->stderr) {
+            $this->stderr = fopen('php://stderr', 'w');
+        }
+        if (!$this->stdout) {
+            $this->stdout = fopen('php://stdout', 'w');
+        }
+        if (!$this->stdin) {
+            $this->stdin = fopen('php://stdin', 'r');
+        }
+
+        // @codeCoverageIgnoreEnd
+
+
+        try {
+
+            list($options, $positional) = $this->parseArguments($argv);
+
+            if (isset($options['q'])) {
+                $this->quiet = true;
+            }
+            $this->log($this->colorize('green', "sabre/vobject ") . $this->colorize('yellow', Version::VERSION));
+
+            foreach ($options as $name => $value) {
+
+                switch ($name) {
+
+                    case 'q' :
+                        // Already handled earlier.
+                        break;
+                    case 'h' :
+                    case 'help' :
+                        $this->showHelp();
+                        return 0;
+                        break;
+                    case 'format' :
+                        switch ($value) {
+
+                            // jcard/jcal documents
+                            case 'jcard' :
+                            case 'jcal' :
+
+                            // specific document versions
+                            case 'vcard21' :
+                            case 'vcard30' :
+                            case 'vcard40' :
+                            case 'icalendar20' :
+
+                            // specific formats
+                            case 'json' :
+                            case 'mimedir' :
+
+                            // icalendar/vcad
+                            case 'icalendar' :
+                            case 'vcard' :
+                                $this->format = $value;
+                                break;
+
+                            default :
+                                throw new InvalidArgumentException('Unknown format: ' . $value);
+
+                        }
+                        break;
+                    case 'pretty' :
+                        if (version_compare(PHP_VERSION, '5.4.0') >= 0) {
+                            $this->pretty = true;
+                        }
+                        break;
+                    case 'forgiving' :
+                        $this->forgiving = true;
+                        break;
+                    case 'inputformat' :
+                        switch ($value) {
+                            // json formats
+                            case 'jcard' :
+                            case 'jcal' :
+                            case 'json' :
+                                $this->inputFormat = 'json';
+                                break;
+
+                            // mimedir formats
+                            case 'mimedir' :
+                            case 'icalendar' :
+                            case 'vcard' :
+                            case 'vcard21' :
+                            case 'vcard30' :
+                            case 'vcard40' :
+                            case 'icalendar20' :
+
+                                $this->inputFormat = 'mimedir';
+                                break;
+
+                            default :
+                                throw new InvalidArgumentException('Unknown format: ' . $value);
+
+                        }
+                        break;
+                    default :
+                        throw new InvalidArgumentException('Unknown option: ' . $name);
+
+                }
+
+            }
+
+            if (count($positional) === 0) {
+                $this->showHelp();
+                return 1;
+            }
+
+            if (count($positional) === 1) {
+                throw new InvalidArgumentException('Inputfile is a required argument');
+            }
+
+            if (count($positional) > 3) {
+                throw new InvalidArgumentException('Too many arguments');
+            }
+
+            if (!in_array($positional[0], ['validate', 'repair', 'convert', 'color'])) {
+                throw new InvalidArgumentException('Uknown command: ' . $positional[0]);
+            }
+
+        } catch (InvalidArgumentException $e) {
+            $this->showHelp();
+            $this->log('Error: ' . $e->getMessage(), 'red');
+            return 1;
+        }
+
+        $command = $positional[0];
+
+        $this->inputPath = $positional[1];
+        $this->outputPath = isset($positional[2]) ? $positional[2] : '-';
+
+        if ($this->outputPath !== '-') {
+            $this->stdout = fopen($this->outputPath, 'w');
+        }
+
+        if (!$this->inputFormat) {
+            if (substr($this->inputPath, -5) === '.json') {
+                $this->inputFormat = 'json';
+            } else {
+                $this->inputFormat = 'mimedir';
+            }
+        }
+        if (!$this->format) {
+            if (substr($this->outputPath, -5) === '.json') {
+                $this->format = 'json';
+            } else {
+                $this->format = 'mimedir';
+            }
+        }
+
+
+        $realCode = 0;
+
+        try {
+
+            while ($input = $this->readInput()) {
+
+                $returnCode = $this->$command($input);
+                if ($returnCode !== 0) $realCode = $returnCode;
+
+            }
+
+        } catch (EofException $e) {
+            // end of file
+        } catch (\Exception $e) {
+            $this->log('Error: ' . $e->getMessage(), 'red');
+            return 2;
+        }
+
+        return $realCode;
+
+    }
+
+    /**
+     * Shows the help message.
+     *
+     * @return void
+     */
+    protected function showHelp() {
+
+        $this->log('Usage:', 'yellow');
+        $this->log("  vobject [options] command [arguments]");
+        $this->log('');
+        $this->log('Options:', 'yellow');
+        $this->log($this->colorize('green', '  -q            ') . "Don't output anything.");
+        $this->log($this->colorize('green', '  -help -h      ') . "Display this help message.");
+        $this->log($this->colorize('green', '  --format      ') . "Convert to a specific format. Must be one of: vcard, vcard21,");
+        $this->log($this->colorize('green', '  --forgiving   ') . "Makes the parser less strict.");
+        $this->log("                vcard30, vcard40, icalendar20, jcal, jcard, json, mimedir.");
+        $this->log($this->colorize('green', '  --inputformat ') . "If the input format cannot be guessed from the extension, it");
+        $this->log("                must be specified here.");
+        // Only PHP 5.4 and up
+        if (version_compare(PHP_VERSION, '5.4.0') >= 0) {
+            $this->log($this->colorize('green', '  --pretty      ') . "json pretty-print.");
+        }
+        $this->log('');
+        $this->log('Commands:', 'yellow');
+        $this->log($this->colorize('green', '  validate') . ' source_file              Validates a file for correctness.');
+        $this->log($this->colorize('green', '  repair') . ' source_file [output_file]  Repairs a file.');
+        $this->log($this->colorize('green', '  convert') . ' source_file [output_file] Converts a file.');
+        $this->log($this->colorize('green', '  color') . ' source_file                 Colorize a file, useful for debbugging.');
+        $this->log(
+        <<<HELP
+
+If source_file is set as '-', STDIN will be used.
+If output_file is omitted, STDOUT will be used.
+All other output is sent to STDERR.
+
+HELP
+        );
+
+        $this->log('Examples:', 'yellow');
+        $this->log('   vobject convert contact.vcf contact.json');
+        $this->log('   vobject convert --format=vcard40 old.vcf new.vcf');
+        $this->log('   vobject convert --inputformat=json --format=mimedir - -');
+        $this->log('   vobject color calendar.ics');
+        $this->log('');
+        $this->log('https://github.com/fruux/sabre-vobject', 'purple');
+
+    }
+
+    /**
+     * Validates a VObject file.
+     *
+     * @param Component $vObj
+     *
+     * @return int
+     */
+    protected function validate(Component $vObj) {
+
+        $returnCode = 0;
+
+        switch ($vObj->name) {
+            case 'VCALENDAR' :
+                $this->log("iCalendar: " . (string)$vObj->VERSION);
+                break;
+            case 'VCARD' :
+                $this->log("vCard: " . (string)$vObj->VERSION);
+                break;
+        }
+
+        $warnings = $vObj->validate();
+        if (!count($warnings)) {
+            $this->log("  No warnings!");
+        } else {
+
+            $levels = [
+                1 => 'REPAIRED',
+                2 => 'WARNING',
+                3 => 'ERROR',
+            ];
+            $returnCode = 2;
+            foreach ($warnings as $warn) {
+
+                $extra = '';
+                if ($warn['node'] instanceof Property) {
+                    $extra = ' (property: "' . $warn['node']->name . '")';
+                }
+                $this->log("  [" . $levels[$warn['level']] . '] ' . $warn['message'] . $extra);
+
+            }
+
+        }
+
+        return $returnCode;
+
+    }
+
+    /**
+     * Repairs a VObject file.
+     *
+     * @param Component $vObj
+     *
+     * @return int
+     */
+    protected function repair(Component $vObj) {
+
+        $returnCode = 0;
+
+        switch ($vObj->name) {
+            case 'VCALENDAR' :
+                $this->log("iCalendar: " . (string)$vObj->VERSION);
+                break;
+            case 'VCARD' :
+                $this->log("vCard: " . (string)$vObj->VERSION);
+                break;
+        }
+
+        $warnings = $vObj->validate(Node::REPAIR);
+        if (!count($warnings)) {
+            $this->log("  No warnings!");
+        } else {
+
+            $levels = [
+                1 => 'REPAIRED',
+                2 => 'WARNING',
+                3 => 'ERROR',
+            ];
+            $returnCode = 2;
+            foreach ($warnings as $warn) {
+
+                $extra = '';
+                if ($warn['node'] instanceof Property) {
+                    $extra = ' (property: "' . $warn['node']->name . '")';
+                }
+                $this->log("  [" . $levels[$warn['level']] . '] ' . $warn['message'] . $extra);
+
+            }
+
+        }
+        fwrite($this->stdout, $vObj->serialize());
+
+        return $returnCode;
+
+    }
+
+    /**
+     * Converts a vObject file to a new format.
+     *
+     * @param Component $vObj
+     *
+     * @return int
+     */
+    protected function convert($vObj) {
+
+        $json = false;
+        $convertVersion = null;
+        $forceInput = null;
+
+        switch ($this->format) {
+            case 'json' :
+                $json = true;
+                if ($vObj->name === 'VCARD') {
+                    $convertVersion = Document::VCARD40;
+                }
+                break;
+            case 'jcard' :
+                $json = true;
+                $forceInput = 'VCARD';
+                $convertVersion = Document::VCARD40;
+                break;
+            case 'jcal' :
+                $json = true;
+                $forceInput = 'VCALENDAR';
+                break;
+            case 'mimedir' :
+            case 'icalendar' :
+            case 'icalendar20' :
+            case 'vcard' :
+                break;
+            case 'vcard21' :
+                $convertVersion = Document::VCARD21;
+                break;
+            case 'vcard30' :
+                $convertVersion = Document::VCARD30;
+                break;
+            case 'vcard40' :
+                $convertVersion = Document::VCARD40;
+                break;
+
+        }
+
+        if ($forceInput && $vObj->name !== $forceInput) {
+            throw new \Exception('You cannot convert a ' . strtolower($vObj->name) . ' to ' . $this->format);
+        }
+        if ($convertVersion) {
+            $vObj = $vObj->convert($convertVersion);
+        }
+        if ($json) {
+            $jsonOptions = 0;
+            if ($this->pretty) {
+                $jsonOptions = JSON_PRETTY_PRINT;
+            }
+            fwrite($this->stdout, json_encode($vObj->jsonSerialize(), $jsonOptions));
+        } else {
+            fwrite($this->stdout, $vObj->serialize());
+        }
+
+        return 0;
+
+    }
+
+    /**
+     * Colorizes a file.
+     *
+     * @param Component $vObj
+     *
+     * @return int
+     */
+    protected function color($vObj) {
+
+        fwrite($this->stdout, $this->serializeComponent($vObj));
+
+    }
+
+    /**
+     * Returns an ansi color string for a color name.
+     *
+     * @param string $color
+     *
+     * @return string
+     */
+    protected function colorize($color, $str, $resetTo = 'default') {
+
+        $colors = [
+            'cyan'    => '1;36',
+            'red'     => '1;31',
+            'yellow'  => '1;33',
+            'blue'    => '0;34',
+            'green'   => '0;32',
+            'default' => '0',
+            'purple'  => '0;35',
+        ];
+        return "\033[" . $colors[$color] . 'm' . $str . "\033[" . $colors[$resetTo] . "m";
+
+    }
+
+    /**
+     * Writes out a string in specific color.
+     *
+     * @param string $color
+     * @param string $str
+     *
+     * @return void
+     */
+    protected function cWrite($color, $str) {
+
+        fwrite($this->stdout, $this->colorize($color, $str));
+
+    }
+
+    protected function serializeComponent(Component $vObj) {
+
+        $this->cWrite('cyan', 'BEGIN');
+        $this->cWrite('red', ':');
+        $this->cWrite('yellow', $vObj->name . "\n");
+
+        /**
+         * Gives a component a 'score' for sorting purposes.
+         *
+         * This is solely used by the childrenSort method.
+         *
+         * A higher score means the item will be lower in the list.
+         * To avoid score collisions, each "score category" has a reasonable
+         * space to accomodate elements. The $key is added to the $score to
+         * preserve the original relative order of elements.
+         *
+         * @param int $key
+         * @param array $array
+         *
+         * @return int
+         */
+        $sortScore = function($key, $array) {
+
+            if ($array[$key] instanceof Component) {
+
+                // We want to encode VTIMEZONE first, this is a personal
+                // preference.
+                if ($array[$key]->name === 'VTIMEZONE') {
+                    $score = 300000000;
+                    return $score + $key;
+                } else {
+                    $score = 400000000;
+                    return $score + $key;
+                }
+            } else {
+                // Properties get encoded first
+                // VCARD version 4.0 wants the VERSION property to appear first
+                if ($array[$key] instanceof Property) {
+                    if ($array[$key]->name === 'VERSION') {
+                        $score = 100000000;
+                        return $score + $key;
+                    } else {
+                        // All other properties
+                        $score = 200000000;
+                        return $score + $key;
+                    }
+                }
+            }
+
+        };
+
+        $children = $vObj->children();
+        $tmp = $children;
+        uksort(
+            $children,
+            function($a, $b) use ($sortScore, $tmp) {
+
+                $sA = $sortScore($a, $tmp);
+                $sB = $sortScore($b, $tmp);
+
+                return $sA - $sB;
+
+            }
+        );
+
+        foreach ($children as $child) {
+            if ($child instanceof Component) {
+                $this->serializeComponent($child);
+            } else {
+                $this->serializeProperty($child);
+            }
+        }
+
+        $this->cWrite('cyan', 'END');
+        $this->cWrite('red', ':');
+        $this->cWrite('yellow', $vObj->name . "\n");
+
+    }
+
+    /**
+     * Colorizes a property.
+     *
+     * @param Property $property
+     *
+     * @return void
+     */
+    protected function serializeProperty(Property $property) {
+
+        if ($property->group) {
+            $this->cWrite('default', $property->group);
+            $this->cWrite('red', '.');
+        }
+
+        $this->cWrite('yellow', $property->name);
+
+        foreach ($property->parameters as $param) {
+
+            $this->cWrite('red', ';');
+            $this->cWrite('blue', $param->serialize());
+
+        }
+        $this->cWrite('red', ':');
+
+        if ($property instanceof Property\Binary) {
+
+            $this->cWrite('default', 'embedded binary stripped. (' . strlen($property->getValue()) . ' bytes)');
+
+        } else {
+
+            $parts = $property->getParts();
+            $first1 = true;
+            // Looping through property values
+            foreach ($parts as $part) {
+                if ($first1) {
+                    $first1 = false;
+                } else {
+                    $this->cWrite('red', $property->delimiter);
+                }
+                $first2 = true;
+                // Looping through property sub-values
+                foreach ((array)$part as $subPart) {
+                    if ($first2) {
+                        $first2 = false;
+                    } else {
+                        // The sub-value delimiter is always comma
+                        $this->cWrite('red', ',');
+                    }
+
+                    $subPart = strtr(
+                        $subPart,
+                        [
+                            '\\' => $this->colorize('purple', '\\\\', 'green'),
+                            ';'  => $this->colorize('purple', '\;', 'green'),
+                            ','  => $this->colorize('purple', '\,', 'green'),
+                            "\n" => $this->colorize('purple', "\\n\n\t", 'green'),
+                            "\r" => "",
+                        ]
+                    );
+
+                    $this->cWrite('green', $subPart);
+                }
+            }
+
+        }
+        $this->cWrite("default", "\n");
+
+    }
+
+    /**
+     * Parses the list of arguments.
+     *
+     * @param array $argv
+     *
+     * @return void
+     */
+    protected function parseArguments(array $argv) {
+
+        $positional = [];
+        $options = [];
+
+        for ($ii = 0; $ii < count($argv); $ii++) {
+
+            // Skipping the first argument.
+            if ($ii === 0) continue;
+
+            $v = $argv[$ii];
+
+            if (substr($v, 0, 2) === '--') {
+                // This is a long-form option.
+                $optionName = substr($v, 2);
+                $optionValue = true;
+                if (strpos($optionName, '=')) {
+                    list($optionName, $optionValue) = explode('=', $optionName);
+                }
+                $options[$optionName] = $optionValue;
+            } elseif (substr($v, 0, 1) === '-' && strlen($v) > 1) {
+                // This is a short-form option.
+                foreach (str_split(substr($v, 1)) as $option) {
+                    $options[$option] = true;
+                }
+
+            } else {
+
+                $positional[] = $v;
+
+            }
+
+        }
+
+        return [$options, $positional];
+
+    }
+
+    protected $parser;
+
+    /**
+     * Reads the input file.
+     *
+     * @return Component
+     */
+    protected function readInput() {
+
+        if (!$this->parser) {
+            if ($this->inputPath !== '-') {
+                $this->stdin = fopen($this->inputPath, 'r');
+            }
+
+            if ($this->inputFormat === 'mimedir') {
+                $this->parser = new Parser\MimeDir($this->stdin, ($this->forgiving ? Reader::OPTION_FORGIVING : 0));
+            } else {
+                $this->parser = new Parser\Json($this->stdin, ($this->forgiving ? Reader::OPTION_FORGIVING : 0));
+            }
+        }
+
+        return $this->parser->parse();
+
+    }
+
+    /**
+     * Sends a message to STDERR.
+     *
+     * @param string $msg
+     *
+     * @return void
+     */
+    protected function log($msg, $color = 'default') {
+
+        if (!$this->quiet) {
+            if ($color !== 'default') {
+                $msg = $this->colorize($color, $msg);
+            }
+            fwrite($this->stderr, $msg . "\n");
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Component.php b/vendor/sabre/vobject/lib/Component.php
new file mode 100644
index 000000000..9a10ed3f8
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component.php
@@ -0,0 +1,700 @@
+<?php
+
+namespace Sabre\VObject;
+
+use Sabre\Xml;
+
+/**
+ * Component.
+ *
+ * A component represents a group of properties, such as VCALENDAR, VEVENT, or
+ * VCARD.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Component extends Node {
+
+    /**
+     * Component name.
+     *
+     * This will contain a string such as VEVENT, VTODO, VCALENDAR, VCARD.
+     *
+     * @var string
+     */
+    public $name;
+
+    /**
+     * A list of properties and/or sub-components.
+     *
+     * @var array
+     */
+    protected $children = [];
+
+    /**
+     * Creates a new component.
+     *
+     * You can specify the children either in key=>value syntax, in which case
+     * properties will automatically be created, or you can just pass a list of
+     * Component and Property object.
+     *
+     * By default, a set of sensible values will be added to the component. For
+     * an iCalendar object, this may be something like CALSCALE:GREGORIAN. To
+     * ensure that this does not happen, set $defaults to false.
+     *
+     * @param Document $root
+     * @param string $name such as VCALENDAR, VEVENT.
+     * @param array $children
+     * @param bool $defaults
+     *
+     * @return void
+     */
+    function __construct(Document $root, $name, array $children = [], $defaults = true) {
+
+        $this->name = strtoupper($name);
+        $this->root = $root;
+
+        if ($defaults) {
+            // This is a terribly convoluted way to do this, but this ensures
+            // that the order of properties as they are specified in both
+            // defaults and the childrens list, are inserted in the object in a
+            // natural way.
+            $list = $this->getDefaults();
+            $nodes = [];
+            foreach ($children as $key => $value) {
+                if ($value instanceof Node) {
+                    if (isset($list[$value->name])) {
+                        unset($list[$value->name]);
+                    }
+                    $nodes[] = $value;
+                } else {
+                    $list[$key] = $value;
+                }
+            }
+            foreach ($list as $key => $value) {
+                $this->add($key, $value);
+            }
+            foreach ($nodes as $node) {
+                $this->add($node);
+            }
+        } else {
+            foreach ($children as $k => $child) {
+                if ($child instanceof Node) {
+                    // Component or Property
+                    $this->add($child);
+                } else {
+
+                    // Property key=>value
+                    $this->add($k, $child);
+                }
+            }
+        }
+
+    }
+
+    /**
+     * Adds a new property or component, and returns the new item.
+     *
+     * This method has 3 possible signatures:
+     *
+     * add(Component $comp) // Adds a new component
+     * add(Property $prop)  // Adds a new property
+     * add($name, $value, array $parameters = []) // Adds a new property
+     * add($name, array $children = []) // Adds a new component
+     * by name.
+     *
+     * @return Node
+     */
+    function add() {
+
+        $arguments = func_get_args();
+
+        if ($arguments[0] instanceof Node) {
+            if (isset($arguments[1])) {
+                throw new \InvalidArgumentException('The second argument must not be specified, when passing a VObject Node');
+            }
+            $arguments[0]->parent = $this;
+            $newNode = $arguments[0];
+
+        } elseif (is_string($arguments[0])) {
+
+            $newNode = call_user_func_array([$this->root, 'create'], $arguments);
+
+        } else {
+
+            throw new \InvalidArgumentException('The first argument must either be a \\Sabre\\VObject\\Node or a string');
+
+        }
+
+        $name = $newNode->name;
+        if (isset($this->children[$name])) {
+            $this->children[$name][] = $newNode;
+        } else {
+            $this->children[$name] = [$newNode];
+        }
+        return $newNode;
+
+    }
+
+    /**
+     * This method removes a component or property from this component.
+     *
+     * You can either specify the item by name (like DTSTART), in which case
+     * all properties/components with that name will be removed, or you can
+     * pass an instance of a property or component, in which case only that
+     * exact item will be removed.
+     *
+     * @param string|Property|Component $item
+     * @return void
+     */
+    function remove($item) {
+
+        if (is_string($item)) {
+            // If there's no dot in the name, it's an exact property name and
+            // we can just wipe out all those properties.
+            //
+            if (strpos($item, '.') === false) {
+                unset($this->children[strtoupper($item)]);
+                return;
+            }
+            // If there was a dot, we need to ask select() to help us out and
+            // then we just call remove recursively.
+            foreach ($this->select($item) as $child) {
+
+                $this->remove($child);
+
+            }
+        } else {
+            foreach ($this->select($item->name) as $k => $child) {
+                if ($child === $item) {
+                    unset($this->children[$item->name][$k]);
+                    return;
+                }
+            }
+        }
+
+        throw new \InvalidArgumentException('The item you passed to remove() was not a child of this component');
+
+    }
+
+    /**
+     * Returns a flat list of all the properties and components in this
+     * component.
+     *
+     * @return array
+     */
+    function children() {
+
+        $result = [];
+        foreach ($this->children as $childGroup) {
+            $result = array_merge($result, $childGroup);
+        }
+        return $result;
+
+    }
+
+    /**
+     * This method only returns a list of sub-components. Properties are
+     * ignored.
+     *
+     * @return array
+     */
+    function getComponents() {
+
+        $result = [];
+
+        foreach ($this->children as $childGroup) {
+            foreach ($childGroup as $child) {
+                if ($child instanceof self) {
+                    $result[] = $child;
+                }
+            }
+        }
+        return $result;
+
+    }
+
+    /**
+     * Returns an array with elements that match the specified name.
+     *
+     * This function is also aware of MIME-Directory groups (as they appear in
+     * vcards). This means that if a property is grouped as "HOME.EMAIL", it
+     * will also be returned when searching for just "EMAIL". If you want to
+     * search for a property in a specific group, you can select on the entire
+     * string ("HOME.EMAIL"). If you want to search on a specific property that
+     * has not been assigned a group, specify ".EMAIL".
+     *
+     * @param string $name
+     * @return array
+     */
+    function select($name) {
+
+        $group = null;
+        $name = strtoupper($name);
+        if (strpos($name, '.') !== false) {
+            list($group, $name) = explode('.', $name, 2);
+        }
+        if ($name === '') $name = null;
+
+        if (!is_null($name)) {
+
+            $result = isset($this->children[$name]) ? $this->children[$name] : [];
+
+            if (is_null($group)) {
+                return $result;
+            } else {
+                // If we have a group filter as well, we need to narrow it down
+                // more.
+                return array_filter(
+                    $result,
+                    function($child) use ($group) {
+
+                        return $child instanceof Property && strtoupper($child->group) === $group;
+
+                    }
+                );
+            }
+
+        }
+
+        // If we got to this point, it means there was no 'name' specified for
+        // searching, implying that this is a group-only search.
+        $result = [];
+        foreach ($this->children as $childGroup) {
+
+            foreach ($childGroup as $child) {
+
+                if ($child instanceof Property && strtoupper($child->group) === $group) {
+                    $result[] = $child;
+                }
+
+            }
+
+        }
+        return $result;
+
+    }
+
+    /**
+     * Turns the object back into a serialized blob.
+     *
+     * @return string
+     */
+    function serialize() {
+
+        $str = "BEGIN:" . $this->name . "\r\n";
+
+        /**
+         * Gives a component a 'score' for sorting purposes.
+         *
+         * This is solely used by the childrenSort method.
+         *
+         * A higher score means the item will be lower in the list.
+         * To avoid score collisions, each "score category" has a reasonable
+         * space to accomodate elements. The $key is added to the $score to
+         * preserve the original relative order of elements.
+         *
+         * @param int $key
+         * @param array $array
+         *
+         * @return int
+         */
+        $sortScore = function($key, $array) {
+
+            if ($array[$key] instanceof Component) {
+
+                // We want to encode VTIMEZONE first, this is a personal
+                // preference.
+                if ($array[$key]->name === 'VTIMEZONE') {
+                    $score = 300000000;
+                    return $score + $key;
+                } else {
+                    $score = 400000000;
+                    return $score + $key;
+                }
+            } else {
+                // Properties get encoded first
+                // VCARD version 4.0 wants the VERSION property to appear first
+                if ($array[$key] instanceof Property) {
+                    if ($array[$key]->name === 'VERSION') {
+                        $score = 100000000;
+                        return $score + $key;
+                    } else {
+                        // All other properties
+                        $score = 200000000;
+                        return $score + $key;
+                    }
+                }
+            }
+
+        };
+
+        $children = $this->children();
+        $tmp = $children;
+        uksort(
+            $children,
+            function($a, $b) use ($sortScore, $tmp) {
+
+                $sA = $sortScore($a, $tmp);
+                $sB = $sortScore($b, $tmp);
+
+                return $sA - $sB;
+
+            }
+        );
+
+        foreach ($children as $child) $str .= $child->serialize();
+        $str .= "END:" . $this->name . "\r\n";
+
+        return $str;
+
+    }
+
+    /**
+     * This method returns an array, with the representation as it should be
+     * encoded in JSON. This is used to create jCard or jCal documents.
+     *
+     * @return array
+     */
+    function jsonSerialize() {
+
+        $components = [];
+        $properties = [];
+
+        foreach ($this->children as $childGroup) {
+            foreach ($childGroup as $child) {
+                if ($child instanceof self) {
+                    $components[] = $child->jsonSerialize();
+                } else {
+                    $properties[] = $child->jsonSerialize();
+                }
+            }
+        }
+
+        return [
+            strtolower($this->name),
+            $properties,
+            $components
+        ];
+
+    }
+
+    /**
+     * This method serializes the data into XML. This is used to create xCard or
+     * xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    function xmlSerialize(Xml\Writer $writer) {
+
+        $components = [];
+        $properties = [];
+
+        foreach ($this->children as $childGroup) {
+            foreach ($childGroup as $child) {
+                if ($child instanceof self) {
+                    $components[] = $child;
+                } else {
+                    $properties[] = $child;
+                }
+            }
+        }
+
+        $writer->startElement(strtolower($this->name));
+
+        if (!empty($properties)) {
+
+            $writer->startElement('properties');
+
+            foreach ($properties as $property) {
+                $property->xmlSerialize($writer);
+            }
+
+            $writer->endElement();
+
+        }
+
+        if (!empty($components)) {
+
+            $writer->startElement('components');
+
+            foreach ($components as $component) {
+                $component->xmlSerialize($writer);
+            }
+
+            $writer->endElement();
+        }
+
+        $writer->endElement();
+
+    }
+
+    /**
+     * This method should return a list of default property values.
+     *
+     * @return array
+     */
+    protected function getDefaults() {
+
+        return [];
+
+    }
+
+    /* Magic property accessors {{{ */
+
+    /**
+     * Using 'get' you will either get a property or component.
+     *
+     * If there were no child-elements found with the specified name,
+     * null is returned.
+     *
+     * To use this, this may look something like this:
+     *
+     * $event = $calendar->VEVENT;
+     *
+     * @param string $name
+     *
+     * @return Property
+     */
+    function __get($name) {
+
+        if ($name === 'children') {
+
+            throw new \RuntimeException('Starting sabre/vobject 4.0 the children property is now protected. You should use the children() method instead');
+
+        }
+
+        $matches = $this->select($name);
+        if (count($matches) === 0) {
+            return;
+        } else {
+            $firstMatch = current($matches);
+            /** @var $firstMatch Property */
+            $firstMatch->setIterator(new ElementList(array_values($matches)));
+            return $firstMatch;
+        }
+
+    }
+
+    /**
+     * This method checks if a sub-element with the specified name exists.
+     *
+     * @param string $name
+     *
+     * @return bool
+     */
+    function __isset($name) {
+
+        $matches = $this->select($name);
+        return count($matches) > 0;
+
+    }
+
+    /**
+     * Using the setter method you can add properties or subcomponents.
+     *
+     * You can either pass a Component, Property
+     * object, or a string to automatically create a Property.
+     *
+     * If the item already exists, it will be removed. If you want to add
+     * a new item with the same name, always use the add() method.
+     *
+     * @param string $name
+     * @param mixed $value
+     *
+     * @return void
+     */
+    function __set($name, $value) {
+
+        $name = strtoupper($name);
+        $this->remove($name);
+        if ($value instanceof self || $value instanceof Property) {
+            $this->add($value);
+        } else {
+            $this->add($name, $value);
+        }
+    }
+
+    /**
+     * Removes all properties and components within this component with the
+     * specified name.
+     *
+     * @param string $name
+     *
+     * @return void
+     */
+    function __unset($name) {
+
+        $this->remove($name);
+
+    }
+
+    /* }}} */
+
+    /**
+     * This method is automatically called when the object is cloned.
+     * Specifically, this will ensure all child elements are also cloned.
+     *
+     * @return void
+     */
+    function __clone() {
+
+        foreach ($this->children as $childName => $childGroup) {
+            foreach ($childGroup as $key => $child) {
+                $clonedChild = clone $child;
+                $clonedChild->parent = $this;
+                $clonedChild->root = $this->root;
+                $this->children[$childName][$key] = $clonedChild;
+            }
+        }
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * It is also possible to specify defaults and severity levels for
+     * violating the rule.
+     *
+     * See the VEVENT implementation for getValidationRules for a more complex
+     * example.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [];
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *   Node::PROFILE_CARDDAV - Validate the vCard for CardDAV purposes.
+     *   Node::PROFILE_CALDAV - Validate the iCalendar for CalDAV purposes.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on).
+     *   2 - A warning.
+     *   3 - An error.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $rules = $this->getValidationRules();
+        $defaults = $this->getDefaults();
+
+        $propertyCounters = [];
+
+        $messages = [];
+
+        foreach ($this->children() as $child) {
+            $name = strtoupper($child->name);
+            if (!isset($propertyCounters[$name])) {
+                $propertyCounters[$name] = 1;
+            } else {
+                $propertyCounters[$name]++;
+            }
+            $messages = array_merge($messages, $child->validate($options));
+        }
+
+        foreach ($rules as $propName => $rule) {
+
+            switch ($rule) {
+                case '0' :
+                    if (isset($propertyCounters[$propName])) {
+                        $messages[] = [
+                            'level'   => 3,
+                            'message' => $propName . ' MUST NOT appear in a ' . $this->name . ' component',
+                            'node'    => $this,
+                        ];
+                    }
+                    break;
+                case '1' :
+                    if (!isset($propertyCounters[$propName]) || $propertyCounters[$propName] !== 1) {
+                        $repaired = false;
+                        if ($options & self::REPAIR && isset($defaults[$propName])) {
+                            $this->add($propName, $defaults[$propName]);
+                            $repaired = true;
+                        }
+                        $messages[] = [
+                            'level'   => $repaired ? 1 : 3,
+                            'message' => $propName . ' MUST appear exactly once in a ' . $this->name . ' component',
+                            'node'    => $this,
+                        ];
+                    }
+                    break;
+                case '+' :
+                    if (!isset($propertyCounters[$propName]) || $propertyCounters[$propName] < 1) {
+                        $messages[] = [
+                            'level'   => 3,
+                            'message' => $propName . ' MUST appear at least once in a ' . $this->name . ' component',
+                            'node'    => $this,
+                        ];
+                    }
+                    break;
+                case '*' :
+                    break;
+                case '?' :
+                    if (isset($propertyCounters[$propName]) && $propertyCounters[$propName] > 1) {
+                        $messages[] = [
+                            'level'   => 3,
+                            'message' => $propName . ' MUST NOT appear more than once in a ' . $this->name . ' component',
+                            'node'    => $this,
+                        ];
+                    }
+                    break;
+
+            }
+
+        }
+        return $messages;
+
+    }
+
+    /**
+     * Call this method on a document if you're done using it.
+     *
+     * It's intended to remove all circular references, so PHP can easily clean
+     * it up.
+     *
+     * @return void
+     */
+    function destroy() {
+
+        parent::destroy();
+        foreach ($this->children as $childGroup) {
+            foreach ($childGroup as $child) {
+                $child->destroy();
+            }
+        }
+        $this->children = [];
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Component/Available.php b/vendor/sabre/vobject/lib/Component/Available.php
new file mode 100644
index 000000000..b3aaf08af
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/Available.php
@@ -0,0 +1,126 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use Sabre\VObject;
+
+/**
+ * The Available sub-component.
+ *
+ * This component adds functionality to a component, specific for AVAILABLE
+ * components.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Ivan Enderlin
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Available extends VObject\Component {
+
+    /**
+     * Returns the 'effective start' and 'effective end' of this VAVAILABILITY
+     * component.
+     *
+     * We use the DTSTART and DTEND or DURATION to determine this.
+     *
+     * The returned value is an array containing DateTimeImmutable instances.
+     * If either the start or end is 'unbounded' its value will be null
+     * instead.
+     *
+     * @return array
+     */
+    function getEffectiveStartEnd() {
+
+        $effectiveStart = $this->DTSTART->getDateTime();
+        if (isset($this->DTEND)) {
+            $effectiveEnd = $this->DTEND->getDateTime();
+        } else {
+            $effectiveEnd = $effectiveStart->add(VObject\DateTimeParser::parseDuration($this->DURATION));
+        }
+
+        return [$effectiveStart, $effectiveEnd];
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'UID'     => 1,
+            'DTSTART' => 1,
+            'DTSTAMP' => 1,
+
+            'DTEND'    => '?',
+            'DURATION' => '?',
+
+            'CREATED'       => '?',
+            'DESCRIPTION'   => '?',
+            'LAST-MODIFIED' => '?',
+            'RECURRENCE-ID' => '?',
+            'RRULE'         => '?',
+            'SUMMARY'       => '?',
+
+            'CATEGORIES' => '*',
+            'COMMENT'    => '*',
+            'CONTACT'    => '*',
+            'EXDATE'     => '*',
+            'RDATE'      => '*',
+
+            'AVAILABLE' => '*',
+        ];
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *   Node::PROFILE_CARDDAV - Validate the vCard for CardDAV purposes.
+     *   Node::PROFILE_CALDAV - Validate the iCalendar for CalDAV purposes.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on).
+     *   2 - A warning.
+     *   3 - An error.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $result = parent::validate($options);
+
+        if (isset($this->DTEND) && isset($this->DURATION)) {
+            $result[] = [
+                'level'   => 3,
+                'message' => 'DTEND and DURATION cannot both be present',
+                'node'    => $this
+            ];
+        }
+
+        return $result;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VAlarm.php b/vendor/sabre/vobject/lib/Component/VAlarm.php
index 2f86c44fd..8cbd572e6 100644
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VAlarm.php
+++ b/vendor/sabre/vobject/lib/Component/VAlarm.php
@@ -1,16 +1,20 @@
 <?php
 
 namespace Sabre\VObject\Component;
+
 use Sabre\VObject;
+use Sabre\VObject\InvalidDataException;
+use DateTimeInterface;
+use DateTimeImmutable;
 
 /**
- * VAlarm component
+ * VAlarm component.
  *
  * This component contains some additional functionality specific for VALARMs.
  *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
  * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ * @license http://sabre.io/license/ Modified BSD License
  */
 class VAlarm extends VObject\Component {
 
@@ -19,12 +23,12 @@ class VAlarm extends VObject\Component {
      *
      * This ignores repeated alarm, only the first trigger is returned.
      *
-     * @return DateTime
+     * @return DateTimeImmutable
      */
-    public function getEffectiveTriggerTime() {
+    function getEffectiveTriggerTime() {
 
         $trigger = $this->TRIGGER;
-        if(!isset($trigger['VALUE']) || strtoupper($trigger['VALUE']) === 'DURATION') {
+        if (!isset($trigger['VALUE']) || strtoupper($trigger['VALUE']) === 'DURATION') {
             $triggerDuration = VObject\DateTimeParser::parseDuration($this->TRIGGER);
             $related = (isset($trigger['RELATED']) && strtoupper($trigger['RELATED']) == 'END') ? 'END' : 'START';
 
@@ -37,28 +41,28 @@ class VAlarm extends VObject\Component {
                     $propName = 'DTSTART';
                 }
 
-                $effectiveTrigger = clone $parentComponent->$propName->getDateTime();
-                $effectiveTrigger->add($triggerDuration);
+                $effectiveTrigger = $parentComponent->$propName->getDateTime();
+                $effectiveTrigger = $effectiveTrigger->add($triggerDuration);
             } else {
                 if ($parentComponent->name === 'VTODO') {
                     $endProp = 'DUE';
                 } elseif ($parentComponent->name === 'VEVENT') {
                     $endProp = 'DTEND';
                 } else {
-                    throw new \LogicException('time-range filters on VALARM components are only supported when they are a child of VTODO or VEVENT');
+                    throw new InvalidDataException('time-range filters on VALARM components are only supported when they are a child of VTODO or VEVENT');
                 }
 
                 if (isset($parentComponent->$endProp)) {
-                    $effectiveTrigger = clone $parentComponent->$endProp->getDateTime();
-                    $effectiveTrigger->add($triggerDuration);
+                    $effectiveTrigger = $parentComponent->$endProp->getDateTime();
+                    $effectiveTrigger = $effectiveTrigger->add($triggerDuration);
                 } elseif (isset($parentComponent->DURATION)) {
-                    $effectiveTrigger = clone $parentComponent->DTSTART->getDateTime();
+                    $effectiveTrigger = $parentComponent->DTSTART->getDateTime();
                     $duration = VObject\DateTimeParser::parseDuration($parentComponent->DURATION);
-                    $effectiveTrigger->add($duration);
-                    $effectiveTrigger->add($triggerDuration);
+                    $effectiveTrigger = $effectiveTrigger->add($duration);
+                    $effectiveTrigger = $effectiveTrigger->add($triggerDuration);
                 } else {
-                    $effectiveTrigger = clone $parentComponent->DTSTART->getDateTime();
-                    $effectiveTrigger->add($triggerDuration);
+                    $effectiveTrigger = $parentComponent->DTSTART->getDateTime();
+                    $effectiveTrigger = $effectiveTrigger->add($triggerDuration);
                 }
             }
         } else {
@@ -75,24 +79,25 @@ class VAlarm extends VObject\Component {
      * The rules used to determine if an event falls within the specified
      * time-range is based on the CalDAV specification.
      *
-     * @param \DateTime $start
-     * @param \DateTime $end
+     * @param DateTime $start
+     * @param DateTime $end
+     *
      * @return bool
      */
-    public function isInTimeRange(\DateTime $start, \DateTime $end) {
+    function isInTimeRange(DateTimeInterface $start, DateTimeInterface $end) {
 
         $effectiveTrigger = $this->getEffectiveTriggerTime();
 
         if (isset($this->DURATION)) {
             $duration = VObject\DateTimeParser::parseDuration($this->DURATION);
-            $repeat = (string)$this->repeat;
+            $repeat = (string)$this->REPEAT;
             if (!$repeat) {
                 $repeat = 1;
             }
 
             $period = new \DatePeriod($effectiveTrigger, $duration, (int)$repeat);
 
-            foreach($period as $occurrence) {
+            foreach ($period as $occurrence) {
 
                 if ($start <= $occurrence && $end > $occurrence) {
                     return true;
@@ -105,4 +110,33 @@ class VAlarm extends VObject\Component {
 
     }
 
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'ACTION'  => 1,
+            'TRIGGER' => 1,
+
+            'DURATION' => '?',
+            'REPEAT'   => '?',
+
+            'ATTACH' => '?',
+        ];
+
+    }
+
 }
diff --git a/vendor/sabre/vobject/lib/Component/VAvailability.php b/vendor/sabre/vobject/lib/Component/VAvailability.php
new file mode 100644
index 000000000..66b3310c5
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VAvailability.php
@@ -0,0 +1,156 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use DateTimeInterface;
+use Sabre\VObject;
+
+/**
+ * The VAvailability component.
+ *
+ * This component adds functionality to a component, specific for VAVAILABILITY
+ * components.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Ivan Enderlin
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VAvailability extends VObject\Component {
+
+    /**
+     * Returns true or false depending on if the event falls in the specified
+     * time-range. This is used for filtering purposes.
+     *
+     * The rules used to determine if an event falls within the specified
+     * time-range is based on:
+     *
+     * https://tools.ietf.org/html/draft-daboo-calendar-availability-05#section-3.1
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     *
+     * @return bool
+     */
+    function isInTimeRange(DateTimeInterface $start, DateTimeInterface $end) {
+
+        list($effectiveStart, $effectiveEnd) = $this->getEffectiveStartEnd();
+        return (
+            (is_null($effectiveStart) || $start < $effectiveEnd) &&
+            (is_null($effectiveEnd) || $end > $effectiveStart)
+        );
+
+    }
+
+    /**
+     * Returns the 'effective start' and 'effective end' of this VAVAILABILITY
+     * component.
+     *
+     * We use the DTSTART and DTEND or DURATION to determine this.
+     *
+     * The returned value is an array containing DateTimeImmutable instances.
+     * If either the start or end is 'unbounded' its value will be null
+     * instead.
+     *
+     * @return array
+     */
+    function getEffectiveStartEnd() {
+
+        $effectiveStart = null;
+        $effectiveEnd = null;
+
+        if (isset($this->DTSTART)) {
+            $effectiveStart = $this->DTSTART->getDateTime();
+        }
+        if (isset($this->DTEND)) {
+            $effectiveEnd = $this->DTEND->getDateTime();
+        } elseif ($effectiveStart && isset($this->DURATION)) {
+            $effectiveEnd = $effectiveStart->add(VObject\DateTimeParser::parseDuration($this->DURATION));
+        }
+
+        return [$effectiveStart, $effectiveEnd];
+
+    }
+
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'UID'     => 1,
+            'DTSTAMP' => 1,
+
+            'BUSYTYPE'      => '?',
+            'CLASS'         => '?',
+            'CREATED'       => '?',
+            'DESCRIPTION'   => '?',
+            'DTSTART'       => '?',
+            'LAST-MODIFIED' => '?',
+            'ORGANIZER'     => '?',
+            'PRIORITY'      => '?',
+            'SEQUENCE'      => '?',
+            'SUMMARY'       => '?',
+            'URL'           => '?',
+            'DTEND'         => '?',
+            'DURATION'      => '?',
+
+            'CATEGORIES' => '*',
+            'COMMENT'    => '*',
+            'CONTACT'    => '*',
+        ];
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *   Node::PROFILE_CARDDAV - Validate the vCard for CardDAV purposes.
+     *   Node::PROFILE_CALDAV - Validate the iCalendar for CalDAV purposes.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on).
+     *   2 - A warning.
+     *   3 - An error.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $result = parent::validate($options);
+
+        if (isset($this->DTEND) && isset($this->DURATION)) {
+            $result[] = [
+                'level'   => 3,
+                'message' => 'DTEND and DURATION cannot both be present',
+                'node'    => $this
+            ];
+        }
+
+        return $result;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Component/VCalendar.php b/vendor/sabre/vobject/lib/Component/VCalendar.php
new file mode 100644
index 000000000..988db9dc2
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VCalendar.php
@@ -0,0 +1,561 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use DateTimeInterface;
+use DateTimeZone;
+use Sabre\VObject;
+use Sabre\VObject\Component;
+use Sabre\VObject\Property;
+use Sabre\VObject\Recur\EventIterator;
+use Sabre\VObject\Recur\NoInstancesException;
+use Sabre\VObject\InvalidDataException;
+
+/**
+ * The VCalendar component.
+ *
+ * This component adds functionality to a component, specific for a VCALENDAR.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VCalendar extends VObject\Document {
+
+    /**
+     * The default name for this component.
+     *
+     * This should be 'VCALENDAR' or 'VCARD'.
+     *
+     * @var string
+     */
+    static $defaultName = 'VCALENDAR';
+
+    /**
+     * This is a list of components, and which classes they should map to.
+     *
+     * @var array
+     */
+    static $componentMap = [
+        'VCALENDAR'     => 'Sabre\\VObject\\Component\\VCalendar',
+        'VALARM'        => 'Sabre\\VObject\\Component\\VAlarm',
+        'VEVENT'        => 'Sabre\\VObject\\Component\\VEvent',
+        'VFREEBUSY'     => 'Sabre\\VObject\\Component\\VFreeBusy',
+        'VAVAILABILITY' => 'Sabre\\VObject\\Component\\VAvailability',
+        'AVAILABLE'     => 'Sabre\\VObject\\Component\\Available',
+        'VJOURNAL'      => 'Sabre\\VObject\\Component\\VJournal',
+        'VTIMEZONE'     => 'Sabre\\VObject\\Component\\VTimeZone',
+        'VTODO'         => 'Sabre\\VObject\\Component\\VTodo',
+    ];
+
+    /**
+     * List of value-types, and which classes they map to.
+     *
+     * @var array
+     */
+    static $valueMap = [
+        'BINARY'           => 'Sabre\\VObject\\Property\\Binary',
+        'BOOLEAN'          => 'Sabre\\VObject\\Property\\Boolean',
+        'CAL-ADDRESS'      => 'Sabre\\VObject\\Property\\ICalendar\\CalAddress',
+        'DATE'             => 'Sabre\\VObject\\Property\\ICalendar\\Date',
+        'DATE-TIME'        => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'DURATION'         => 'Sabre\\VObject\\Property\\ICalendar\\Duration',
+        'FLOAT'            => 'Sabre\\VObject\\Property\\FloatValue',
+        'INTEGER'          => 'Sabre\\VObject\\Property\\IntegerValue',
+        'PERIOD'           => 'Sabre\\VObject\\Property\\ICalendar\\Period',
+        'RECUR'            => 'Sabre\\VObject\\Property\\ICalendar\\Recur',
+        'TEXT'             => 'Sabre\\VObject\\Property\\Text',
+        'TIME'             => 'Sabre\\VObject\\Property\\Time',
+        'UNKNOWN'          => 'Sabre\\VObject\\Property\\Unknown', // jCard / jCal-only.
+        'URI'              => 'Sabre\\VObject\\Property\\Uri',
+        'UTC-OFFSET'       => 'Sabre\\VObject\\Property\\UtcOffset',
+    ];
+
+    /**
+     * List of properties, and which classes they map to.
+     *
+     * @var array
+     */
+    static $propertyMap = [
+        // Calendar properties
+        'CALSCALE'      => 'Sabre\\VObject\\Property\\FlatText',
+        'METHOD'        => 'Sabre\\VObject\\Property\\FlatText',
+        'PRODID'        => 'Sabre\\VObject\\Property\\FlatText',
+        'VERSION'       => 'Sabre\\VObject\\Property\\FlatText',
+
+        // Component properties
+        'ATTACH'            => 'Sabre\\VObject\\Property\\Uri',
+        'CATEGORIES'        => 'Sabre\\VObject\\Property\\Text',
+        'CLASS'             => 'Sabre\\VObject\\Property\\FlatText',
+        'COMMENT'           => 'Sabre\\VObject\\Property\\FlatText',
+        'DESCRIPTION'       => 'Sabre\\VObject\\Property\\FlatText',
+        'GEO'               => 'Sabre\\VObject\\Property\\FloatValue',
+        'LOCATION'          => 'Sabre\\VObject\\Property\\FlatText',
+        'PERCENT-COMPLETE'  => 'Sabre\\VObject\\Property\\IntegerValue',
+        'PRIORITY'          => 'Sabre\\VObject\\Property\\IntegerValue',
+        'RESOURCES'         => 'Sabre\\VObject\\Property\\Text',
+        'STATUS'            => 'Sabre\\VObject\\Property\\FlatText',
+        'SUMMARY'           => 'Sabre\\VObject\\Property\\FlatText',
+
+        // Date and Time Component Properties
+        'COMPLETED'     => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'DTEND'         => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'DUE'           => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'DTSTART'       => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'DURATION'      => 'Sabre\\VObject\\Property\\ICalendar\\Duration',
+        'FREEBUSY'      => 'Sabre\\VObject\\Property\\ICalendar\\Period',
+        'TRANSP'        => 'Sabre\\VObject\\Property\\FlatText',
+
+        // Time Zone Component Properties
+        'TZID'          => 'Sabre\\VObject\\Property\\FlatText',
+        'TZNAME'        => 'Sabre\\VObject\\Property\\FlatText',
+        'TZOFFSETFROM'  => 'Sabre\\VObject\\Property\\UtcOffset',
+        'TZOFFSETTO'    => 'Sabre\\VObject\\Property\\UtcOffset',
+        'TZURL'         => 'Sabre\\VObject\\Property\\Uri',
+
+        // Relationship Component Properties
+        'ATTENDEE'      => 'Sabre\\VObject\\Property\\ICalendar\\CalAddress',
+        'CONTACT'       => 'Sabre\\VObject\\Property\\FlatText',
+        'ORGANIZER'     => 'Sabre\\VObject\\Property\\ICalendar\\CalAddress',
+        'RECURRENCE-ID' => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'RELATED-TO'    => 'Sabre\\VObject\\Property\\FlatText',
+        'URL'           => 'Sabre\\VObject\\Property\\Uri',
+        'UID'           => 'Sabre\\VObject\\Property\\FlatText',
+
+        // Recurrence Component Properties
+        'EXDATE'        => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'RDATE'         => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'RRULE'         => 'Sabre\\VObject\\Property\\ICalendar\\Recur',
+        'EXRULE'        => 'Sabre\\VObject\\Property\\ICalendar\\Recur', // Deprecated since rfc5545
+
+        // Alarm Component Properties
+        'ACTION'        => 'Sabre\\VObject\\Property\\FlatText',
+        'REPEAT'        => 'Sabre\\VObject\\Property\\IntegerValue',
+        'TRIGGER'       => 'Sabre\\VObject\\Property\\ICalendar\\Duration',
+
+        // Change Management Component Properties
+        'CREATED'       => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'DTSTAMP'       => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'LAST-MODIFIED' => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'SEQUENCE'      => 'Sabre\\VObject\\Property\\IntegerValue',
+
+        // Request Status
+        'REQUEST-STATUS' => 'Sabre\\VObject\\Property\\Text',
+
+        // Additions from draft-daboo-valarm-extensions-04
+        'ALARM-AGENT'    => 'Sabre\\VObject\\Property\\Text',
+        'ACKNOWLEDGED'   => 'Sabre\\VObject\\Property\\ICalendar\\DateTime',
+        'PROXIMITY'      => 'Sabre\\VObject\\Property\\Text',
+        'DEFAULT-ALARM'  => 'Sabre\\VObject\\Property\\Boolean',
+
+        // Additions from draft-daboo-calendar-availability-05
+        'BUSYTYPE'       => 'Sabre\\VObject\\Property\\Text',
+
+    ];
+
+    /**
+     * Returns the current document type.
+     *
+     * @return int
+     */
+    function getDocumentType() {
+
+        return self::ICALENDAR20;
+
+    }
+
+    /**
+     * Returns a list of all 'base components'. For instance, if an Event has
+     * a recurrence rule, and one instance is overridden, the overridden event
+     * will have the same UID, but will be excluded from this list.
+     *
+     * VTIMEZONE components will always be excluded.
+     *
+     * @param string $componentName filter by component name
+     *
+     * @return VObject\Component[]
+     */
+    function getBaseComponents($componentName = null) {
+
+        $isBaseComponent = function($component) {
+
+            if (!$component instanceof VObject\Component) {
+                return false;
+            }
+            if ($component->name === 'VTIMEZONE') {
+                return false;
+            }
+            if (isset($component->{'RECURRENCE-ID'})) {
+                return false;
+            }
+            return true;
+
+        };
+
+        if ($componentName) {
+            // Early exit
+            return array_filter(
+                $this->select($componentName),
+                $isBaseComponent
+            );
+        }
+
+        $components = [];
+        foreach ($this->children as $childGroup) {
+
+            foreach ($childGroup as $child) {
+
+                if (!$child instanceof Component) {
+                    // If one child is not a component, they all are so we skip
+                    // the entire group.
+                    continue 2;
+                }
+                if ($isBaseComponent($child)) {
+                    $components[] = $child;
+                }
+
+            }
+
+        }
+        return $components;
+
+    }
+
+    /**
+     * Returns the first component that is not a VTIMEZONE, and does not have
+     * an RECURRENCE-ID.
+     *
+     * If there is no such component, null will be returned.
+     *
+     * @param string $componentName filter by component name
+     *
+     * @return VObject\Component|null
+     */
+    function getBaseComponent($componentName = null) {
+
+        $isBaseComponent = function($component) {
+
+            if (!$component instanceof VObject\Component) {
+                return false;
+            }
+            if ($component->name === 'VTIMEZONE') {
+                return false;
+            }
+            if (isset($component->{'RECURRENCE-ID'})) {
+                return false;
+            }
+            return true;
+
+        };
+
+        if ($componentName) {
+            foreach ($this->select($componentName) as $child) {
+                if ($isBaseComponent($child)) {
+                    return $child;
+                }
+            }
+            return null;
+        }
+
+        // Searching all components
+        foreach ($this->children as $childGroup) {
+            foreach ($childGroup as $child) {
+                if ($isBaseComponent($child)) {
+                    return $child;
+                }
+            }
+
+        }
+        return null;
+
+    }
+
+    /**
+     * Expand all events in this VCalendar object and return a new VCalendar
+     * with the expanded events.
+     *
+     * If this calendar object, has events with recurrence rules, this method
+     * can be used to expand the event into multiple sub-events.
+     *
+     * Each event will be stripped from it's recurrence information, and only
+     * the instances of the event in the specified timerange will be left
+     * alone.
+     *
+     * In addition, this method will cause timezone information to be stripped,
+     * and normalized to UTC.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     * @param DateTimeZone $timeZone reference timezone for floating dates and
+     *                     times.
+     * @return VCalendar
+     */
+    function expand(DateTimeInterface $start, DateTimeInterface $end, DateTimeZone $timeZone = null) {
+
+        $newChildren = [];
+        $recurringEvents = [];
+
+        if (!$timeZone) {
+            $timeZone = new DateTimeZone('UTC');
+        }
+
+        $stripTimezones = function(Component $component) use ($timeZone, &$stripTimezones) {
+
+            foreach ($component->children() as $componentChild) {
+                if ($componentChild instanceof Property\ICalendar\DateTime && $componentChild->hasTime()) {
+
+                    $dt = $componentChild->getDateTimes($timeZone);
+                    // We only need to update the first timezone, because
+                    // setDateTimes will match all other timezones to the
+                    // first.
+                    $dt[0] = $dt[0]->setTimeZone(new DateTimeZone('UTC'));
+                    $componentChild->setDateTimes($dt);
+                } elseif ($componentChild instanceof Component) {
+                    $stripTimezones($componentChild);
+                }
+
+            }
+            return $component;
+
+        };
+
+        foreach ($this->children() as $child) {
+
+            if ($child instanceof Property && $child->name !== 'PRODID') {
+                // We explictly want to ignore PRODID, because we want to
+                // overwrite it with our own.
+                $newChildren[] = clone $child;
+            } elseif ($child instanceof Component && $child->name !== 'VTIMEZONE') {
+
+                // We're also stripping all VTIMEZONE objects because we're
+                // converting everything to UTC.
+                if ($child->name === 'VEVENT' && (isset($child->{'RECURRENCE-ID'}) || isset($child->RRULE) || isset($child->RDATE))) {
+                    // Handle these a bit later.
+                    $uid = (string)$child->UID;
+                    if (!$uid) {
+                        throw new InvalidDataException('Every VEVENT object must have a UID property');
+                    }
+                    if (isset($recurringEvents[$uid])) {
+                        $recurringEvents[$uid][] = clone $child;
+                    } else {
+                        $recurringEvents[$uid] = [clone $child];
+                    }
+                } elseif ($child->name === 'VEVENT' && $child->isInTimeRange($start, $end)) {
+                    $newChildren[] = $stripTimezones(clone $child);
+                }
+
+            }
+
+        }
+
+        foreach ($recurringEvents as $events) {
+
+            try {
+                $it = new EventIterator($events, $timeZone);
+
+            } catch (NoInstancesException $e) {
+                // This event is recurring, but it doesn't have a single
+                // instance. We are skipping this event from the output
+                // entirely.
+                continue;
+            }
+            $it->fastForward($start);
+
+            while ($it->valid() && $it->getDTStart() < $end) {
+
+                if ($it->getDTEnd() > $start) {
+
+                    $newChildren[] = $stripTimezones($it->getEventObject());
+
+                }
+                $it->next();
+
+            }
+
+        }
+
+        return new self($newChildren);
+
+    }
+
+    /**
+     * This method should return a list of default property values.
+     *
+     * @return array
+     */
+    protected function getDefaults() {
+
+        return [
+            'VERSION'  => '2.0',
+            'PRODID'   => '-//Sabre//Sabre VObject ' . VObject\Version::VERSION . '//EN',
+            'CALSCALE' => 'GREGORIAN',
+        ];
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'PRODID'  => 1,
+            'VERSION' => 1,
+
+            'CALSCALE' => '?',
+            'METHOD'   => '?',
+        ];
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *   Node::PROFILE_CARDDAV - Validate the vCard for CardDAV purposes.
+     *   Node::PROFILE_CALDAV - Validate the iCalendar for CalDAV purposes.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on).
+     *   2 - A warning.
+     *   3 - An error.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $warnings = parent::validate($options);
+
+        if ($ver = $this->VERSION) {
+            if ((string)$ver !== '2.0') {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'Only iCalendar version 2.0 as defined in rfc5545 is supported.',
+                    'node'    => $this,
+                ];
+            }
+
+        }
+
+        $uidList = [];
+        $componentsFound = 0;
+        $componentTypes = [];
+
+        foreach ($this->children() as $child) {
+            if ($child instanceof Component) {
+                $componentsFound++;
+
+                if (!in_array($child->name, ['VEVENT', 'VTODO', 'VJOURNAL'])) {
+                    continue;
+                }
+                $componentTypes[] = $child->name;
+
+                $uid = (string)$child->UID;
+                $isMaster = isset($child->{'RECURRENCE-ID'}) ? 0 : 1;
+                if (isset($uidList[$uid])) {
+                    $uidList[$uid]['count']++;
+                    if ($isMaster && $uidList[$uid]['hasMaster']) {
+                        $warnings[] = [
+                            'level'   => 3,
+                            'message' => 'More than one master object was found for the object with UID ' . $uid,
+                            'node'    => $this,
+                        ];
+                    }
+                    $uidList[$uid]['hasMaster'] += $isMaster;
+                } else {
+                    $uidList[$uid] = [
+                        'count'     => 1,
+                        'hasMaster' => $isMaster,
+                    ];
+                }
+
+            }
+        }
+
+        if ($componentsFound === 0) {
+            $warnings[] = [
+                'level'   => 3,
+                'message' => 'An iCalendar object must have at least 1 component.',
+                'node'    => $this,
+            ];
+        }
+
+        if ($options & self::PROFILE_CALDAV) {
+            if (count($uidList) > 1) {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'A calendar object on a CalDAV server may only have components with the same UID.',
+                    'node'    => $this,
+                ];
+            }
+            if (count($componentTypes) === 0) {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'A calendar object on a CalDAV server must have at least 1 component (VTODO, VEVENT, VJOURNAL).',
+                    'node'    => $this,
+                ];
+            }
+            if (count(array_unique($componentTypes)) > 1) {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'A calendar object on a CalDAV server may only have 1 type of component (VEVENT, VTODO or VJOURNAL).',
+                    'node'    => $this,
+                ];
+            }
+
+            if (isset($this->METHOD)) {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'A calendar object on a CalDAV server MUST NOT have a METHOD property.',
+                    'node'    => $this,
+                ];
+            }
+        }
+
+        return $warnings;
+
+    }
+
+    /**
+     * Returns all components with a specific UID value.
+     *
+     * @return array
+     */
+    function getByUID($uid) {
+
+        return array_filter($this->getComponents(), function($item) use ($uid) {
+
+            if (!$itemUid = $item->select('UID')) {
+                return false;
+            }
+            $itemUid = current($itemUid)->getValue();
+            return $uid === $itemUid;
+
+        });
+
+    }
+
+
+}
diff --git a/vendor/sabre/vobject/lib/Component/VCard.php b/vendor/sabre/vobject/lib/Component/VCard.php
new file mode 100644
index 000000000..3c05191a9
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VCard.php
@@ -0,0 +1,553 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use Sabre\VObject;
+use Sabre\Xml;
+
+/**
+ * The VCard component.
+ *
+ * This component represents the BEGIN:VCARD and END:VCARD found in every
+ * vcard.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VCard extends VObject\Document {
+
+    /**
+     * The default name for this component.
+     *
+     * This should be 'VCALENDAR' or 'VCARD'.
+     *
+     * @var string
+     */
+    static $defaultName = 'VCARD';
+
+    /**
+     * Caching the version number.
+     *
+     * @var int
+     */
+    private $version = null;
+
+    /**
+     * This is a list of components, and which classes they should map to.
+     *
+     * @var array
+     */
+    static $componentMap = [
+        'VCARD' => 'Sabre\\VObject\\Component\\VCard',
+    ];
+
+    /**
+     * List of value-types, and which classes they map to.
+     *
+     * @var array
+     */
+    static $valueMap = [
+        'BINARY'           => 'Sabre\\VObject\\Property\\Binary',
+        'BOOLEAN'          => 'Sabre\\VObject\\Property\\Boolean',
+        'CONTENT-ID'       => 'Sabre\\VObject\\Property\\FlatText',   // vCard 2.1 only
+        'DATE'             => 'Sabre\\VObject\\Property\\VCard\\Date',
+        'DATE-TIME'        => 'Sabre\\VObject\\Property\\VCard\\DateTime',
+        'DATE-AND-OR-TIME' => 'Sabre\\VObject\\Property\\VCard\\DateAndOrTime', // vCard only
+        'FLOAT'            => 'Sabre\\VObject\\Property\\FloatValue',
+        'INTEGER'          => 'Sabre\\VObject\\Property\\IntegerValue',
+        'LANGUAGE-TAG'     => 'Sabre\\VObject\\Property\\VCard\\LanguageTag',
+        'TIMESTAMP'        => 'Sabre\\VObject\\Property\\VCard\\TimeStamp',
+        'TEXT'             => 'Sabre\\VObject\\Property\\Text',
+        'TIME'             => 'Sabre\\VObject\\Property\\Time',
+        'UNKNOWN'          => 'Sabre\\VObject\\Property\\Unknown', // jCard / jCal-only.
+        'URI'              => 'Sabre\\VObject\\Property\\Uri',
+        'URL'              => 'Sabre\\VObject\\Property\\Uri', // vCard 2.1 only
+        'UTC-OFFSET'       => 'Sabre\\VObject\\Property\\UtcOffset',
+    ];
+
+    /**
+     * List of properties, and which classes they map to.
+     *
+     * @var array
+     */
+    static $propertyMap = [
+
+        // vCard 2.1 properties and up
+        'N'       => 'Sabre\\VObject\\Property\\Text',
+        'FN'      => 'Sabre\\VObject\\Property\\FlatText',
+        'PHOTO'   => 'Sabre\\VObject\\Property\\Binary',
+        'BDAY'    => 'Sabre\\VObject\\Property\\VCard\\DateAndOrTime',
+        'ADR'     => 'Sabre\\VObject\\Property\\Text',
+        'LABEL'   => 'Sabre\\VObject\\Property\\FlatText', // Removed in vCard 4.0
+        'TEL'     => 'Sabre\\VObject\\Property\\FlatText',
+        'EMAIL'   => 'Sabre\\VObject\\Property\\FlatText',
+        'MAILER'  => 'Sabre\\VObject\\Property\\FlatText', // Removed in vCard 4.0
+        'GEO'     => 'Sabre\\VObject\\Property\\FlatText',
+        'TITLE'   => 'Sabre\\VObject\\Property\\FlatText',
+        'ROLE'    => 'Sabre\\VObject\\Property\\FlatText',
+        'LOGO'    => 'Sabre\\VObject\\Property\\Binary',
+        // 'AGENT'   => 'Sabre\\VObject\\Property\\',      // Todo: is an embedded vCard. Probably rare, so
+                                 // not supported at the moment
+        'ORG'     => 'Sabre\\VObject\\Property\\Text',
+        'NOTE'    => 'Sabre\\VObject\\Property\\FlatText',
+        'REV'     => 'Sabre\\VObject\\Property\\VCard\\TimeStamp',
+        'SOUND'   => 'Sabre\\VObject\\Property\\FlatText',
+        'URL'     => 'Sabre\\VObject\\Property\\Uri',
+        'UID'     => 'Sabre\\VObject\\Property\\FlatText',
+        'VERSION' => 'Sabre\\VObject\\Property\\FlatText',
+        'KEY'     => 'Sabre\\VObject\\Property\\FlatText',
+        'TZ'      => 'Sabre\\VObject\\Property\\Text',
+
+        // vCard 3.0 properties
+        'CATEGORIES'  => 'Sabre\\VObject\\Property\\Text',
+        'SORT-STRING' => 'Sabre\\VObject\\Property\\FlatText',
+        'PRODID'      => 'Sabre\\VObject\\Property\\FlatText',
+        'NICKNAME'    => 'Sabre\\VObject\\Property\\Text',
+        'CLASS'       => 'Sabre\\VObject\\Property\\FlatText', // Removed in vCard 4.0
+
+        // rfc2739 properties
+        'FBURL'        => 'Sabre\\VObject\\Property\\Uri',
+        'CAPURI'       => 'Sabre\\VObject\\Property\\Uri',
+        'CALURI'       => 'Sabre\\VObject\\Property\\Uri',
+        'CALADRURI'    => 'Sabre\\VObject\\Property\\Uri',
+
+        // rfc4770 properties
+        'IMPP'         => 'Sabre\\VObject\\Property\\Uri',
+
+        // vCard 4.0 properties
+        'SOURCE'       => 'Sabre\\VObject\\Property\\Uri',
+        'XML'          => 'Sabre\\VObject\\Property\\FlatText',
+        'ANNIVERSARY'  => 'Sabre\\VObject\\Property\\VCard\\DateAndOrTime',
+        'CLIENTPIDMAP' => 'Sabre\\VObject\\Property\\Text',
+        'LANG'         => 'Sabre\\VObject\\Property\\VCard\\LanguageTag',
+        'GENDER'       => 'Sabre\\VObject\\Property\\Text',
+        'KIND'         => 'Sabre\\VObject\\Property\\FlatText',
+        'MEMBER'       => 'Sabre\\VObject\\Property\\Uri',
+        'RELATED'      => 'Sabre\\VObject\\Property\\Uri',
+
+        // rfc6474 properties
+        'BIRTHPLACE'    => 'Sabre\\VObject\\Property\\FlatText',
+        'DEATHPLACE'    => 'Sabre\\VObject\\Property\\FlatText',
+        'DEATHDATE'     => 'Sabre\\VObject\\Property\\VCard\\DateAndOrTime',
+
+        // rfc6715 properties
+        'EXPERTISE'     => 'Sabre\\VObject\\Property\\FlatText',
+        'HOBBY'         => 'Sabre\\VObject\\Property\\FlatText',
+        'INTEREST'      => 'Sabre\\VObject\\Property\\FlatText',
+        'ORG-DIRECTORY' => 'Sabre\\VObject\\Property\\FlatText',
+
+    ];
+
+    /**
+     * Returns the current document type.
+     *
+     * @return int
+     */
+    function getDocumentType() {
+
+        if (!$this->version) {
+
+            $version = (string)$this->VERSION;
+
+            switch ($version) {
+                case '2.1' :
+                    $this->version = self::VCARD21;
+                    break;
+                case '3.0' :
+                    $this->version = self::VCARD30;
+                    break;
+                case '4.0' :
+                    $this->version = self::VCARD40;
+                    break;
+                default :
+                    // We don't want to cache the version if it's unknown,
+                    // because we might get a version property in a bit.
+                    return self::UNKNOWN;
+            }
+        }
+
+        return $this->version;
+
+    }
+
+    /**
+     * Converts the document to a different vcard version.
+     *
+     * Use one of the VCARD constants for the target. This method will return
+     * a copy of the vcard in the new version.
+     *
+     * At the moment the only supported conversion is from 3.0 to 4.0.
+     *
+     * If input and output version are identical, a clone is returned.
+     *
+     * @param int $target
+     *
+     * @return VCard
+     */
+    function convert($target) {
+
+        $converter = new VObject\VCardConverter();
+        return $converter->convert($this, $target);
+
+    }
+
+    /**
+     * VCards with version 2.1, 3.0 and 4.0 are found.
+     *
+     * If the VCARD doesn't know its version, 2.1 is assumed.
+     */
+    const DEFAULT_VERSION = self::VCARD21;
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on)
+     *   2 - An inconsequential issue
+     *   3 - A severe issue.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $warnings = [];
+
+        $versionMap = [
+            self::VCARD21 => '2.1',
+            self::VCARD30 => '3.0',
+            self::VCARD40 => '4.0',
+        ];
+
+        $version = $this->select('VERSION');
+        if (count($version) === 1) {
+            $version = (string)$this->VERSION;
+            if ($version !== '2.1' && $version !== '3.0' && $version !== '4.0') {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'Only vcard version 4.0 (RFC6350), version 3.0 (RFC2426) or version 2.1 (icm-vcard-2.1) are supported.',
+                    'node'    => $this,
+                ];
+                if ($options & self::REPAIR) {
+                    $this->VERSION = $versionMap[self::DEFAULT_VERSION];
+                }
+            }
+            if ($version === '2.1' && ($options & self::PROFILE_CARDDAV)) {
+                $warnings[] = [
+                    'level'   => 3,
+                    'message' => 'CardDAV servers are not allowed to accept vCard 2.1.',
+                    'node'    => $this,
+                ];
+            }
+
+        }
+        $uid = $this->select('UID');
+        if (count($uid) === 0) {
+            if ($options & self::PROFILE_CARDDAV) {
+                // Required for CardDAV
+                $warningLevel = 3;
+                $message = 'vCards on CardDAV servers MUST have a UID property.';
+            } else {
+                // Not required for regular vcards
+                $warningLevel = 2;
+                $message = 'Adding a UID to a vCard property is recommended.';
+            }
+            if ($options & self::REPAIR) {
+                $this->UID = VObject\UUIDUtil::getUUID();
+                $warningLevel = 1;
+            }
+            $warnings[] = [
+                'level'   => $warningLevel,
+                'message' => $message,
+                'node'    => $this,
+            ];
+        }
+
+        $fn = $this->select('FN');
+        if (count($fn) !== 1) {
+
+            $repaired = false;
+            if (($options & self::REPAIR) && count($fn) === 0) {
+                // We're going to try to see if we can use the contents of the
+                // N property.
+                if (isset($this->N)) {
+                    $value = explode(';', (string)$this->N);
+                    if (isset($value[1]) && $value[1]) {
+                        $this->FN = $value[1] . ' ' . $value[0];
+                    } else {
+                        $this->FN = $value[0];
+                    }
+                    $repaired = true;
+
+                // Otherwise, the ORG property may work
+                } elseif (isset($this->ORG)) {
+                    $this->FN = (string)$this->ORG;
+                    $repaired = true;
+                }
+
+            }
+            $warnings[] = [
+                'level'   => $repaired ? 1 : 3,
+                'message' => 'The FN property must appear in the VCARD component exactly 1 time',
+                'node'    => $this,
+            ];
+        }
+
+        return array_merge(
+            parent::validate($options),
+            $warnings
+        );
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'ADR'          => '*',
+            'ANNIVERSARY'  => '?',
+            'BDAY'         => '?',
+            'CALADRURI'    => '*',
+            'CALURI'       => '*',
+            'CATEGORIES'   => '*',
+            'CLIENTPIDMAP' => '*',
+            'EMAIL'        => '*',
+            'FBURL'        => '*',
+            'IMPP'         => '*',
+            'GENDER'       => '?',
+            'GEO'          => '*',
+            'KEY'          => '*',
+            'KIND'         => '?',
+            'LANG'         => '*',
+            'LOGO'         => '*',
+            'MEMBER'       => '*',
+            'N'            => '?',
+            'NICKNAME'     => '*',
+            'NOTE'         => '*',
+            'ORG'          => '*',
+            'PHOTO'        => '*',
+            'PRODID'       => '?',
+            'RELATED'      => '*',
+            'REV'          => '?',
+            'ROLE'         => '*',
+            'SOUND'        => '*',
+            'SOURCE'       => '*',
+            'TEL'          => '*',
+            'TITLE'        => '*',
+            'TZ'           => '*',
+            'URL'          => '*',
+            'VERSION'      => '1',
+            'XML'          => '*',
+
+            // FN is commented out, because it's already handled by the
+            // validate function, which may also try to repair it.
+            // 'FN'           => '+',
+            'UID'          => '?',
+        ];
+
+    }
+
+    /**
+     * Returns a preferred field.
+     *
+     * VCards can indicate wether a field such as ADR, TEL or EMAIL is
+     * preferred by specifying TYPE=PREF (vcard 2.1, 3) or PREF=x (vcard 4, x
+     * being a number between 1 and 100).
+     *
+     * If neither of those parameters are specified, the first is returned, if
+     * a field with that name does not exist, null is returned.
+     *
+     * @param string $fieldName
+     *
+     * @return VObject\Property|null
+     */
+    function preferred($propertyName) {
+
+        $preferred = null;
+        $lastPref = 101;
+        foreach ($this->select($propertyName) as $field) {
+
+            $pref = 101;
+            if (isset($field['TYPE']) && $field['TYPE']->has('PREF')) {
+                $pref = 1;
+            } elseif (isset($field['PREF'])) {
+                $pref = $field['PREF']->getValue();
+            }
+
+            if ($pref < $lastPref || is_null($preferred)) {
+                $preferred = $field;
+                $lastPref = $pref;
+            }
+
+        }
+        return $preferred;
+
+    }
+
+    /**
+     * Returns a property with a specific TYPE value (ADR, TEL, or EMAIL).
+     *
+     * This function will return null if the property does not exist. If there are
+     * multiple properties with the same TYPE value, only one will be returned.
+     *
+     * @param string $propertyName
+     * @param string $type
+     *
+     * @return VObject\Property|null
+     */
+    function getByType($propertyName, $type) {
+        foreach ($this->select($propertyName) as $field) {
+            if (isset($field['TYPE']) && $field['TYPE']->has($type)) {
+                return $field;
+            }
+        }
+    }
+
+    /**
+     * This method should return a list of default property values.
+     *
+     * @return array
+     */
+    protected function getDefaults() {
+
+        return [
+            'VERSION' => '4.0',
+            'PRODID'  => '-//Sabre//Sabre VObject ' . VObject\Version::VERSION . '//EN',
+            'UID'     => 'sabre-vobject-' . VObject\UUIDUtil::getUUID(),
+        ];
+
+    }
+
+    /**
+     * This method returns an array, with the representation as it should be
+     * encoded in json. This is used to create jCard or jCal documents.
+     *
+     * @return array
+     */
+    function jsonSerialize() {
+
+        // A vcard does not have sub-components, so we're overriding this
+        // method to remove that array element.
+        $properties = [];
+
+        foreach ($this->children() as $child) {
+            $properties[] = $child->jsonSerialize();
+        }
+
+        return [
+            strtolower($this->name),
+            $properties,
+        ];
+
+    }
+
+    /**
+     * This method serializes the data into XML. This is used to create xCard or
+     * xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    function xmlSerialize(Xml\Writer $writer) {
+
+        $propertiesByGroup = [];
+
+        foreach ($this->children() as $property) {
+
+            $group = $property->group;
+
+            if (!isset($propertiesByGroup[$group])) {
+                $propertiesByGroup[$group] = [];
+            }
+
+            $propertiesByGroup[$group][] = $property;
+
+        }
+
+        $writer->startElement(strtolower($this->name));
+
+        foreach ($propertiesByGroup as $group => $properties) {
+
+            if (!empty($group)) {
+
+                $writer->startElement('group');
+                $writer->writeAttribute('name', strtolower($group));
+
+            }
+
+            foreach ($properties as $property) {
+                switch ($property->name) {
+
+                    case 'VERSION':
+                        continue;
+
+                    case 'XML':
+                        $value = $property->getParts();
+                        $fragment = new Xml\Element\XmlFragment($value[0]);
+                        $writer->write($fragment);
+                        break;
+
+                    default:
+                        $property->xmlSerialize($writer);
+                        break;
+
+                }
+            }
+
+            if (!empty($group)) {
+                $writer->endElement();
+            }
+
+        }
+
+        $writer->endElement();
+
+    }
+
+    /**
+     * Returns the default class for a property name.
+     *
+     * @param string $propertyName
+     *
+     * @return string
+     */
+    function getClassNameForPropertyName($propertyName) {
+
+        $className = parent::getClassNameForPropertyName($propertyName);
+
+        // In vCard 4, BINARY no longer exists, and we need URI instead.
+        if ($className == 'Sabre\\VObject\\Property\\Binary' && $this->getDocumentType() === self::VCARD40) {
+            return 'Sabre\\VObject\\Property\\Uri';
+        }
+        return $className;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Component/VEvent.php b/vendor/sabre/vobject/lib/Component/VEvent.php
new file mode 100644
index 000000000..7f6861190
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VEvent.php
@@ -0,0 +1,153 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use DateTimeInterface;
+use Sabre\VObject;
+use Sabre\VObject\Recur\EventIterator;
+use Sabre\VObject\Recur\NoInstancesException;
+
+/**
+ * VEvent component.
+ *
+ * This component contains some additional functionality specific for VEVENT's.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VEvent extends VObject\Component {
+
+    /**
+     * Returns true or false depending on if the event falls in the specified
+     * time-range. This is used for filtering purposes.
+     *
+     * The rules used to determine if an event falls within the specified
+     * time-range is based on the CalDAV specification.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     *
+     * @return bool
+     */
+    function isInTimeRange(DateTimeInterface $start, DateTimeInterface $end) {
+
+        if ($this->RRULE) {
+
+            try {
+
+                $it = new EventIterator($this, null, $start->getTimezone());
+
+            } catch (NoInstancesException $e) {
+
+                // If we've catched this exception, there are no instances
+                // for the event that fall into the specified time-range.
+                return false;
+
+            }
+
+            $it->fastForward($start);
+
+            // We fast-forwarded to a spot where the end-time of the
+            // recurrence instance exceeded the start of the requested
+            // time-range.
+            //
+            // If the starttime of the recurrence did not exceed the
+            // end of the time range as well, we have a match.
+            return ($it->getDTStart() < $end && $it->getDTEnd() > $start);
+
+        }
+
+        $effectiveStart = $this->DTSTART->getDateTime($start->getTimezone());
+        if (isset($this->DTEND)) {
+
+            // The DTEND property is considered non inclusive. So for a 3 day
+            // event in july, dtstart and dtend would have to be July 1st and
+            // July 4th respectively.
+            //
+            // See:
+            // http://tools.ietf.org/html/rfc5545#page-54
+            $effectiveEnd = $this->DTEND->getDateTime($end->getTimezone());
+
+        } elseif (isset($this->DURATION)) {
+            $effectiveEnd = $effectiveStart->add(VObject\DateTimeParser::parseDuration($this->DURATION));
+        } elseif (!$this->DTSTART->hasTime()) {
+            $effectiveEnd = $effectiveStart->modify('+1 day');
+        } else {
+            $effectiveEnd = $effectiveStart;
+        }
+        return (
+            ($start < $effectiveEnd) && ($end > $effectiveStart)
+        );
+
+    }
+
+    /**
+     * This method should return a list of default property values.
+     *
+     * @return array
+     */
+    protected function getDefaults() {
+
+        return [
+            'UID'     => 'sabre-vobject-' . VObject\UUIDUtil::getUUID(),
+            'DTSTAMP' => date('Ymd\\THis\\Z'),
+        ];
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        $hasMethod = isset($this->parent->METHOD);
+        return [
+            'UID'           => 1,
+            'DTSTAMP'       => 1,
+            'DTSTART'       => $hasMethod ? '?' : '1',
+            'CLASS'         => '?',
+            'CREATED'       => '?',
+            'DESCRIPTION'   => '?',
+            'GEO'           => '?',
+            'LAST-MODIFIED' => '?',
+            'LOCATION'      => '?',
+            'ORGANIZER'     => '?',
+            'PRIORITY'      => '?',
+            'SEQUENCE'      => '?',
+            'STATUS'        => '?',
+            'SUMMARY'       => '?',
+            'TRANSP'        => '?',
+            'URL'           => '?',
+            'RECURRENCE-ID' => '?',
+            'RRULE'         => '?',
+            'DTEND'         => '?',
+            'DURATION'      => '?',
+
+            'ATTACH'         => '*',
+            'ATTENDEE'       => '*',
+            'CATEGORIES'     => '*',
+            'COMMENT'        => '*',
+            'CONTACT'        => '*',
+            'EXDATE'         => '*',
+            'REQUEST-STATUS' => '*',
+            'RELATED-TO'     => '*',
+            'RESOURCES'      => '*',
+            'RDATE'          => '*',
+        ];
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Component/VFreeBusy.php b/vendor/sabre/vobject/lib/Component/VFreeBusy.php
new file mode 100644
index 000000000..72294cc9f
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VFreeBusy.php
@@ -0,0 +1,102 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use DateTimeInterface;
+use Sabre\VObject;
+
+/**
+ * The VFreeBusy component.
+ *
+ * This component adds functionality to a component, specific for VFREEBUSY
+ * components.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VFreeBusy extends VObject\Component {
+
+    /**
+     * Checks based on the contained FREEBUSY information, if a timeslot is
+     * available.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     *
+     * @return bool
+     */
+    function isFree(DateTimeInterface $start, DatetimeInterface $end) {
+
+        foreach ($this->select('FREEBUSY') as $freebusy) {
+
+            // We are only interested in FBTYPE=BUSY (the default),
+            // FBTYPE=BUSY-TENTATIVE or FBTYPE=BUSY-UNAVAILABLE.
+            if (isset($freebusy['FBTYPE']) && strtoupper(substr((string)$freebusy['FBTYPE'], 0, 4)) !== 'BUSY') {
+                continue;
+            }
+
+            // The freebusy component can hold more than 1 value, separated by
+            // commas.
+            $periods = explode(',', (string)$freebusy);
+
+            foreach ($periods as $period) {
+                // Every period is formatted as [start]/[end]. The start is an
+                // absolute UTC time, the end may be an absolute UTC time, or
+                // duration (relative) value.
+                list($busyStart, $busyEnd) = explode('/', $period);
+
+                $busyStart = VObject\DateTimeParser::parse($busyStart);
+                $busyEnd = VObject\DateTimeParser::parse($busyEnd);
+                if ($busyEnd instanceof \DateInterval) {
+                    $busyEnd = $busyStart->add($busyEnd);
+                }
+
+                if ($start < $busyEnd && $end > $busyStart) {
+                    return false;
+                }
+
+            }
+
+        }
+
+        return true;
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'UID'     => 1,
+            'DTSTAMP' => 1,
+
+            'CONTACT'   => '?',
+            'DTSTART'   => '?',
+            'DTEND'     => '?',
+            'ORGANIZER' => '?',
+            'URL'       => '?',
+
+            'ATTENDEE'       => '*',
+            'COMMENT'        => '*',
+            'FREEBUSY'       => '*',
+            'REQUEST-STATUS' => '*',
+        ];
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Component/VJournal.php b/vendor/sabre/vobject/lib/Component/VJournal.php
new file mode 100644
index 000000000..a1b1a863d
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VJournal.php
@@ -0,0 +1,107 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use DateTimeInterface;
+use Sabre\VObject;
+
+/**
+ * VJournal component.
+ *
+ * This component contains some additional functionality specific for VJOURNALs.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VJournal extends VObject\Component {
+
+    /**
+     * Returns true or false depending on if the event falls in the specified
+     * time-range. This is used for filtering purposes.
+     *
+     * The rules used to determine if an event falls within the specified
+     * time-range is based on the CalDAV specification.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     *
+     * @return bool
+     */
+    function isInTimeRange(DateTimeInterface $start, DateTimeInterface $end) {
+
+        $dtstart = isset($this->DTSTART) ? $this->DTSTART->getDateTime() : null;
+        if ($dtstart) {
+            $effectiveEnd = $dtstart;
+            if (!$this->DTSTART->hasTime()) {
+                $effectiveEnd = $effectiveEnd->modify('+1 day');
+            }
+
+            return ($start <= $effectiveEnd && $end > $dtstart);
+
+        }
+        return false;
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'UID'     => 1,
+            'DTSTAMP' => 1,
+
+            'CLASS'         => '?',
+            'CREATED'       => '?',
+            'DTSTART'       => '?',
+            'LAST-MODIFIED' => '?',
+            'ORGANIZER'     => '?',
+            'RECURRENCE-ID' => '?',
+            'SEQUENCE'      => '?',
+            'STATUS'        => '?',
+            'SUMMARY'       => '?',
+            'URL'           => '?',
+
+            'RRULE' => '?',
+
+            'ATTACH'      => '*',
+            'ATTENDEE'    => '*',
+            'CATEGORIES'  => '*',
+            'COMMENT'     => '*',
+            'CONTACT'     => '*',
+            'DESCRIPTION' => '*',
+            'EXDATE'      => '*',
+            'RELATED-TO'  => '*',
+            'RDATE'       => '*',
+        ];
+
+    }
+
+    /**
+     * This method should return a list of default property values.
+     *
+     * @return array
+     */
+    protected function getDefaults() {
+
+        return [
+            'UID'     => 'sabre-vobject-' . VObject\UUIDUtil::getUUID(),
+            'DTSTAMP' => date('Ymd\\THis\\Z'),
+        ];
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Component/VTimeZone.php b/vendor/sabre/vobject/lib/Component/VTimeZone.php
new file mode 100644
index 000000000..d5d886947
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VTimeZone.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use Sabre\VObject;
+
+/**
+ * The VTimeZone component.
+ *
+ * This component adds functionality to a component, specific for VTIMEZONE
+ * components.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VTimeZone extends VObject\Component {
+
+    /**
+     * Returns the PHP DateTimeZone for this VTIMEZONE component.
+     *
+     * If we can't accurately determine the timezone, this method will return
+     * UTC.
+     *
+     * @return \DateTimeZone
+     */
+    function getTimeZone() {
+
+        return VObject\TimeZoneUtil::getTimeZone((string)$this->TZID, $this->root);
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'TZID' => 1,
+
+            'LAST-MODIFIED' => '?',
+            'TZURL'         => '?',
+
+            // At least 1 STANDARD or DAYLIGHT must appear, or more. But both
+            // cannot appear in the same VTIMEZONE.
+            //
+            // The validator is not specific yet to pick this up, so these
+            // rules are too loose.
+            'STANDARD' => '*',
+            'DAYLIGHT' => '*',
+        ];
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Component/VTodo.php b/vendor/sabre/vobject/lib/Component/VTodo.php
new file mode 100644
index 000000000..144ced694
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Component/VTodo.php
@@ -0,0 +1,193 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use DateTimeInterface;
+use Sabre\VObject;
+
+/**
+ * VTodo component.
+ *
+ * This component contains some additional functionality specific for VTODOs.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VTodo extends VObject\Component {
+
+    /**
+     * Returns true or false depending on if the event falls in the specified
+     * time-range. This is used for filtering purposes.
+     *
+     * The rules used to determine if an event falls within the specified
+     * time-range is based on the CalDAV specification.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     *
+     * @return bool
+     */
+    function isInTimeRange(DateTimeInterface $start, DateTimeInterface $end) {
+
+        $dtstart = isset($this->DTSTART) ? $this->DTSTART->getDateTime() : null;
+        $duration = isset($this->DURATION) ? VObject\DateTimeParser::parseDuration($this->DURATION) : null;
+        $due = isset($this->DUE) ? $this->DUE->getDateTime() : null;
+        $completed = isset($this->COMPLETED) ? $this->COMPLETED->getDateTime() : null;
+        $created = isset($this->CREATED) ? $this->CREATED->getDateTime() : null;
+
+        if ($dtstart) {
+            if ($duration) {
+                $effectiveEnd = $dtstart->add($duration);
+                return $start <= $effectiveEnd && $end > $dtstart;
+            } elseif ($due) {
+                return
+                    ($start < $due || $start <= $dtstart) &&
+                    ($end > $dtstart || $end >= $due);
+            } else {
+                return $start <= $dtstart && $end > $dtstart;
+            }
+        }
+        if ($due) {
+            return ($start < $due && $end >= $due);
+        }
+        if ($completed && $created) {
+            return
+                ($start <= $created || $start <= $completed) &&
+                ($end >= $created || $end >= $completed);
+        }
+        if ($completed) {
+            return ($start <= $completed && $end >= $completed);
+        }
+        if ($created) {
+            return ($end > $created);
+        }
+        return true;
+
+    }
+
+    /**
+     * A simple list of validation rules.
+     *
+     * This is simply a list of properties, and how many times they either
+     * must or must not appear.
+     *
+     * Possible values per property:
+     *   * 0 - Must not appear.
+     *   * 1 - Must appear exactly once.
+     *   * + - Must appear at least once.
+     *   * * - Can appear any number of times.
+     *   * ? - May appear, but not more than once.
+     *
+     * @var array
+     */
+    function getValidationRules() {
+
+        return [
+            'UID'     => 1,
+            'DTSTAMP' => 1,
+
+            'CLASS'         => '?',
+            'COMPLETED'     => '?',
+            'CREATED'       => '?',
+            'DESCRIPTION'   => '?',
+            'DTSTART'       => '?',
+            'GEO'           => '?',
+            'LAST-MODIFIED' => '?',
+            'LOCATION'      => '?',
+            'ORGANIZER'     => '?',
+            'PERCENT'       => '?',
+            'PRIORITY'      => '?',
+            'RECURRENCE-ID' => '?',
+            'SEQUENCE'      => '?',
+            'STATUS'        => '?',
+            'SUMMARY'       => '?',
+            'URL'           => '?',
+
+            'RRULE'    => '?',
+            'DUE'      => '?',
+            'DURATION' => '?',
+
+            'ATTACH'         => '*',
+            'ATTENDEE'       => '*',
+            'CATEGORIES'     => '*',
+            'COMMENT'        => '*',
+            'CONTACT'        => '*',
+            'EXDATE'         => '*',
+            'REQUEST-STATUS' => '*',
+            'RELATED-TO'     => '*',
+            'RESOURCES'      => '*',
+            'RDATE'          => '*',
+        ];
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on)
+     *   2 - An inconsequential issue
+     *   3 - A severe issue.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $result = parent::validate($options);
+        if (isset($this->DUE) && isset($this->DTSTART)) {
+
+            $due = $this->DUE;
+            $dtStart = $this->DTSTART;
+
+            if ($due->getValueType() !== $dtStart->getValueType()) {
+
+                $result[] = [
+                    'level'   => 3,
+                    'message' => 'The value type (DATE or DATE-TIME) must be identical for DUE and DTSTART',
+                    'node'    => $due,
+                ];
+
+            } elseif ($due->getDateTime() < $dtStart->getDateTime()) {
+
+                $result[] = [
+                    'level'   => 3,
+                    'message' => 'DUE must occur after DTSTART',
+                    'node'    => $due,
+                ];
+
+            }
+
+        }
+
+        return $result;
+
+    }
+
+    /**
+     * This method should return a list of default property values.
+     *
+     * @return array
+     */
+    protected function getDefaults() {
+
+        return [
+            'UID'     => 'sabre-vobject-' . VObject\UUIDUtil::getUUID(),
+            'DTSTAMP' => date('Ymd\\THis\\Z'),
+        ];
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/DateTimeParser.php b/vendor/sabre/vobject/lib/DateTimeParser.php
new file mode 100644
index 000000000..fc568abb0
--- /dev/null
+++ b/vendor/sabre/vobject/lib/DateTimeParser.php
@@ -0,0 +1,571 @@
+<?php
+
+namespace Sabre\VObject;
+
+use DateTimeImmutable;
+use DateTimeZone;
+use DateInterval;
+
+/**
+ * DateTimeParser.
+ *
+ * This class is responsible for parsing the several different date and time
+ * formats iCalendar and vCards have.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class DateTimeParser {
+
+    /**
+     * Parses an iCalendar (rfc5545) formatted datetime and returns a
+     * DateTimeImmutable object.
+     *
+     * Specifying a reference timezone is optional. It will only be used
+     * if the non-UTC format is used. The argument is used as a reference, the
+     * returned DateTimeImmutable object will still be in the UTC timezone.
+     *
+     * @param string $dt
+     * @param DateTimeZone $tz
+     *
+     * @return DateTimeImmutable
+     */
+    static function parseDateTime($dt, DateTimeZone $tz = null) {
+
+        // Format is YYYYMMDD + "T" + hhmmss
+        $result = preg_match('/^([0-9]{4})([0-1][0-9])([0-3][0-9])T([0-2][0-9])([0-5][0-9])([0-5][0-9])([Z]?)$/', $dt, $matches);
+
+        if (!$result) {
+            throw new InvalidDataException('The supplied iCalendar datetime value is incorrect: ' . $dt);
+        }
+
+        if ($matches[7] === 'Z' || is_null($tz)) {
+            $tz = new DateTimeZone('UTC');
+        }
+        $date = new DateTimeImmutable($matches[1] . '-' . $matches[2] . '-' . $matches[3] . ' ' . $matches[4] . ':' . $matches[5] . ':' . $matches[6], $tz);
+
+        return $date;
+
+    }
+
+    /**
+     * Parses an iCalendar (rfc5545) formatted date and returns a DateTimeImmutable object.
+     *
+     * @param string $date
+     * @param DateTimeZone $tz
+     *
+     * @return DateTimeImmutable
+     */
+    static function parseDate($date, DateTimeZone $tz = null) {
+
+        // Format is YYYYMMDD
+        $result = preg_match('/^([0-9]{4})([0-1][0-9])([0-3][0-9])$/', $date, $matches);
+
+        if (!$result) {
+            throw new InvalidDataException('The supplied iCalendar date value is incorrect: ' . $date);
+        }
+
+        if (is_null($tz)) {
+            $tz = new DateTimeZone('UTC');
+        }
+
+        $date = new DateTimeImmutable($matches[1] . '-' . $matches[2] . '-' . $matches[3], $tz);
+
+        return $date;
+
+    }
+
+    /**
+     * Parses an iCalendar (RFC5545) formatted duration value.
+     *
+     * This method will either return a DateTimeInterval object, or a string
+     * suitable for strtotime or DateTime::modify.
+     *
+     * @param string $duration
+     * @param bool $asString
+     *
+     * @return DateInterval|string
+     */
+    static function parseDuration($duration, $asString = false) {
+
+        $result = preg_match('/^(?<plusminus>\+|-)?P((?<week>\d+)W)?((?<day>\d+)D)?(T((?<hour>\d+)H)?((?<minute>\d+)M)?((?<second>\d+)S)?)?$/', $duration, $matches);
+        if (!$result) {
+            throw new InvalidDataException('The supplied iCalendar duration value is incorrect: ' . $duration);
+        }
+
+        if (!$asString) {
+
+            $invert = false;
+
+            if ($matches['plusminus'] === '-') {
+                $invert = true;
+            }
+
+            $parts = [
+                'week',
+                'day',
+                'hour',
+                'minute',
+                'second',
+            ];
+
+            foreach ($parts as $part) {
+                $matches[$part] = isset($matches[$part]) && $matches[$part] ? (int)$matches[$part] : 0;
+            }
+
+            // We need to re-construct the $duration string, because weeks and
+            // days are not supported by DateInterval in the same string.
+            $duration = 'P';
+            $days = $matches['day'];
+
+            if ($matches['week']) {
+                $days += $matches['week'] * 7;
+            }
+
+            if ($days) {
+                $duration .= $days . 'D';
+            }
+
+            if ($matches['minute'] || $matches['second'] || $matches['hour']) {
+
+                $duration .= 'T';
+
+                if ($matches['hour']) {
+                    $duration .= $matches['hour'] . 'H';
+                }
+
+                if ($matches['minute']) {
+                    $duration .= $matches['minute'] . 'M';
+                }
+
+                if ($matches['second']) {
+                    $duration .= $matches['second'] . 'S';
+                }
+
+            }
+
+            if ($duration === 'P') {
+                $duration = 'PT0S';
+            }
+
+            $iv = new DateInterval($duration);
+
+            if ($invert) {
+                $iv->invert = true;
+            }
+
+            return $iv;
+
+        }
+
+        $parts = [
+            'week',
+            'day',
+            'hour',
+            'minute',
+            'second',
+        ];
+
+        $newDur = '';
+
+        foreach ($parts as $part) {
+            if (isset($matches[$part]) && $matches[$part]) {
+                $newDur .= ' ' . $matches[$part] . ' ' . $part . 's';
+            }
+        }
+
+        $newDur = ($matches['plusminus'] === '-' ? '-' : '+') . trim($newDur);
+
+        if ($newDur === '+') {
+            $newDur = '+0 seconds';
+        };
+
+        return $newDur;
+
+    }
+
+    /**
+     * Parses either a Date or DateTime, or Duration value.
+     *
+     * @param string $date
+     * @param DateTimeZone|string $referenceTz
+     *
+     * @return DateTimeImmutable|DateInterval
+     */
+    static function parse($date, $referenceTz = null) {
+
+        if ($date[0] === 'P' || ($date[0] === '-' && $date[1] === 'P')) {
+            return self::parseDuration($date);
+        } elseif (strlen($date) === 8) {
+            return self::parseDate($date, $referenceTz);
+        } else {
+            return self::parseDateTime($date, $referenceTz);
+        }
+
+    }
+
+    /**
+     * This method parses a vCard date and or time value.
+     *
+     * This can be used for the DATE, DATE-TIME, TIMESTAMP and
+     * DATE-AND-OR-TIME value.
+     *
+     * This method returns an array, not a DateTime value.
+     *
+     * The elements in the array are in the following order:
+     * year, month, date, hour, minute, second, timezone
+     *
+     * Almost any part of the string may be omitted. It's for example legal to
+     * just specify seconds, leave out the year, etc.
+     *
+     * Timezone is either returned as 'Z' or as '+0800'
+     *
+     * For any non-specified values null is returned.
+     *
+     * List of date formats that are supported:
+     * YYYY
+     * YYYY-MM
+     * YYYYMMDD
+     * --MMDD
+     * ---DD
+     *
+     * YYYY-MM-DD
+     * --MM-DD
+     * ---DD
+     *
+     * List of supported time formats:
+     *
+     * HH
+     * HHMM
+     * HHMMSS
+     * -MMSS
+     * --SS
+     *
+     * HH
+     * HH:MM
+     * HH:MM:SS
+     * -MM:SS
+     * --SS
+     *
+     * A full basic-format date-time string looks like :
+     * 20130603T133901
+     *
+     * A full extended-format date-time string looks like :
+     * 2013-06-03T13:39:01
+     *
+     * Times may be postfixed by a timezone offset. This can be either 'Z' for
+     * UTC, or a string like -0500 or +1100.
+     *
+     * @param string $date
+     *
+     * @return array
+     */
+    static function parseVCardDateTime($date) {
+
+        $regex = '/^
+            (?:  # date part
+                (?:
+                    (?: (?<year> [0-9]{4}) (?: -)?| --)
+                    (?<month> [0-9]{2})?
+                |---)
+                (?<date> [0-9]{2})?
+            )?
+            (?:T  # time part
+                (?<hour> [0-9]{2} | -)
+                (?<minute> [0-9]{2} | -)?
+                (?<second> [0-9]{2})?
+
+                (?: \.[0-9]{3})? # milliseconds
+                (?P<timezone> # timezone offset
+
+                    Z | (?: \+|-)(?: [0-9]{4})
+
+                )?
+
+            )?
+            $/x';
+
+        if (!preg_match($regex, $date, $matches)) {
+
+            // Attempting to parse the extended format.
+            $regex = '/^
+                (?: # date part
+                    (?: (?<year> [0-9]{4}) - | -- )
+                    (?<month> [0-9]{2}) -
+                    (?<date> [0-9]{2})
+                )?
+                (?:T # time part
+
+                    (?: (?<hour> [0-9]{2}) : | -)
+                    (?: (?<minute> [0-9]{2}) : | -)?
+                    (?<second> [0-9]{2})?
+
+                    (?: \.[0-9]{3})? # milliseconds
+                    (?P<timezone> # timezone offset
+
+                        Z | (?: \+|-)(?: [0-9]{2}:[0-9]{2})
+
+                    )?
+
+                )?
+                $/x';
+
+            if (!preg_match($regex, $date, $matches)) {
+                throw new InvalidDataException('Invalid vCard date-time string: ' . $date);
+            }
+
+        }
+        $parts = [
+            'year',
+            'month',
+            'date',
+            'hour',
+            'minute',
+            'second',
+            'timezone'
+        ];
+
+        $result = [];
+        foreach ($parts as $part) {
+
+            if (empty($matches[$part])) {
+                $result[$part] = null;
+            } elseif ($matches[$part] === '-' || $matches[$part] === '--') {
+                $result[$part] = null;
+            } else {
+                $result[$part] = $matches[$part];
+            }
+
+        }
+
+        return $result;
+
+    }
+
+    /**
+     * This method parses a vCard TIME value.
+     *
+     * This method returns an array, not a DateTime value.
+     *
+     * The elements in the array are in the following order:
+     * hour, minute, second, timezone
+     *
+     * Almost any part of the string may be omitted. It's for example legal to
+     * just specify seconds, leave out the hour etc.
+     *
+     * Timezone is either returned as 'Z' or as '+08:00'
+     *
+     * For any non-specified values null is returned.
+     *
+     * List of supported time formats:
+     *
+     * HH
+     * HHMM
+     * HHMMSS
+     * -MMSS
+     * --SS
+     *
+     * HH
+     * HH:MM
+     * HH:MM:SS
+     * -MM:SS
+     * --SS
+     *
+     * A full basic-format time string looks like :
+     * 133901
+     *
+     * A full extended-format time string looks like :
+     * 13:39:01
+     *
+     * Times may be postfixed by a timezone offset. This can be either 'Z' for
+     * UTC, or a string like -0500 or +11:00.
+     *
+     * @param string $date
+     *
+     * @return array
+     */
+    static function parseVCardTime($date) {
+
+        $regex = '/^
+            (?<hour> [0-9]{2} | -)
+            (?<minute> [0-9]{2} | -)?
+            (?<second> [0-9]{2})?
+
+            (?: \.[0-9]{3})? # milliseconds
+            (?P<timezone> # timezone offset
+
+                Z | (?: \+|-)(?: [0-9]{4})
+
+            )?
+            $/x';
+
+
+        if (!preg_match($regex, $date, $matches)) {
+
+            // Attempting to parse the extended format.
+            $regex = '/^
+                (?: (?<hour> [0-9]{2}) : | -)
+                (?: (?<minute> [0-9]{2}) : | -)?
+                (?<second> [0-9]{2})?
+
+                (?: \.[0-9]{3})? # milliseconds
+                (?P<timezone> # timezone offset
+
+                    Z | (?: \+|-)(?: [0-9]{2}:[0-9]{2})
+
+                )?
+                $/x';
+
+            if (!preg_match($regex, $date, $matches)) {
+                throw new InvalidDataException('Invalid vCard time string: ' . $date);
+            }
+
+        }
+        $parts = [
+            'hour',
+            'minute',
+            'second',
+            'timezone'
+        ];
+
+        $result = [];
+        foreach ($parts as $part) {
+
+            if (empty($matches[$part])) {
+                $result[$part] = null;
+            } elseif ($matches[$part] === '-') {
+                $result[$part] = null;
+            } else {
+                $result[$part] = $matches[$part];
+            }
+
+        }
+
+        return $result;
+
+    }
+
+    /**
+     * This method parses a vCard date and or time value.
+     *
+     * This can be used for the DATE, DATE-TIME and
+     * DATE-AND-OR-TIME value.
+     *
+     * This method returns an array, not a DateTime value.
+     * The elements in the array are in the following order:
+     *     year, month, date, hour, minute, second, timezone
+     * Almost any part of the string may be omitted. It's for example legal to
+     * just specify seconds, leave out the year, etc.
+     *
+     * Timezone is either returned as 'Z' or as '+0800'
+     *
+     * For any non-specified values null is returned.
+     *
+     * List of date formats that are supported:
+     *     20150128
+     *     2015-01
+     *     --01
+     *     --0128
+     *     ---28
+     *
+     * List of supported time formats:
+     *     13
+     *     1353
+     *     135301
+     *     -53
+     *     -5301
+     *     --01 (unreachable, see the tests)
+     *     --01Z
+     *     --01+1234
+     *
+     * List of supported date-time formats:
+     *     20150128T13
+     *     --0128T13
+     *     ---28T13
+     *     ---28T1353
+     *     ---28T135301
+     *     ---28T13Z
+     *     ---28T13+1234
+     *
+     * See the regular expressions for all the possible patterns.
+     *
+     * Times may be postfixed by a timezone offset. This can be either 'Z' for
+     * UTC, or a string like -0500 or +1100.
+     *
+     * @param string $date
+     *
+     * @return array
+     */
+    static function parseVCardDateAndOrTime($date) {
+
+        // \d{8}|\d{4}-\d\d|--\d\d(\d\d)?|---\d\d
+        $valueDate     = '/^(?J)(?:' .
+                         '(?<year>\d{4})(?<month>\d\d)(?<date>\d\d)' .
+                         '|(?<year>\d{4})-(?<month>\d\d)' .
+                         '|--(?<month>\d\d)(?<date>\d\d)?' .
+                         '|---(?<date>\d\d)' .
+                         ')$/';
+
+        // (\d\d(\d\d(\d\d)?)?|-\d\d(\d\d)?|--\d\d)(Z|[+\-]\d\d(\d\d)?)?
+        $valueTime     = '/^(?J)(?:' .
+                         '((?<hour>\d\d)((?<minute>\d\d)(?<second>\d\d)?)?' .
+                         '|-(?<minute>\d\d)(?<second>\d\d)?' .
+                         '|--(?<second>\d\d))' .
+                         '(?<timezone>(Z|[+\-]\d\d(\d\d)?))?' .
+                         ')$/';
+
+        // (\d{8}|--\d{4}|---\d\d)T\d\d(\d\d(\d\d)?)?(Z|[+\-]\d\d(\d\d?)?
+        $valueDateTime = '/^(?:' .
+                         '((?<year0>\d{4})(?<month0>\d\d)(?<date0>\d\d)' .
+                         '|--(?<month1>\d\d)(?<date1>\d\d)' .
+                         '|---(?<date2>\d\d))' .
+                         'T' .
+                         '(?<hour>\d\d)((?<minute>\d\d)(?<second>\d\d)?)?' .
+                         '(?<timezone>(Z|[+\-]\d\d(\d\d?)))?' .
+                         ')$/';
+
+        // date-and-or-time is date | date-time | time
+        // in this strict order.
+
+        if (0 === preg_match($valueDate, $date, $matches)
+            && 0 === preg_match($valueDateTime, $date, $matches)
+            && 0 === preg_match($valueTime, $date, $matches)) {
+            throw new InvalidDataException('Invalid vCard date-time string: ' . $date);
+        }
+
+        $parts = [
+            'year'     => null,
+            'month'    => null,
+            'date'     => null,
+            'hour'     => null,
+            'minute'   => null,
+            'second'   => null,
+            'timezone' => null
+        ];
+
+        // The $valueDateTime expression has a bug with (?J) so we simulate it.
+        $parts['date0']  = &$parts['date'];
+        $parts['date1']  = &$parts['date'];
+        $parts['date2']  = &$parts['date'];
+        $parts['month0'] = &$parts['month'];
+        $parts['month1'] = &$parts['month'];
+        $parts['year0']  = &$parts['year'];
+
+        foreach ($parts as $part => &$value) {
+            if (!empty($matches[$part])) {
+                $value = $matches[$part];
+            }
+        }
+
+        unset($parts['date0']);
+        unset($parts['date1']);
+        unset($parts['date2']);
+        unset($parts['month0']);
+        unset($parts['month1']);
+        unset($parts['year0']);
+
+        return $parts;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Document.php b/vendor/sabre/vobject/lib/Document.php
new file mode 100644
index 000000000..03252ab06
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Document.php
@@ -0,0 +1,270 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * Document.
+ *
+ * A document is just like a component, except that it's also the top level
+ * element.
+ *
+ * Both a VCALENDAR and a VCARD are considered documents.
+ *
+ * This class also provides a registry for document types.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+abstract class Document extends Component {
+
+    /**
+     * Unknown document type.
+     */
+    const UNKNOWN = 1;
+
+    /**
+     * vCalendar 1.0.
+     */
+    const VCALENDAR10 = 2;
+
+    /**
+     * iCalendar 2.0.
+     */
+    const ICALENDAR20 = 3;
+
+    /**
+     * vCard 2.1.
+     */
+    const VCARD21 = 4;
+
+    /**
+     * vCard 3.0.
+     */
+    const VCARD30 = 5;
+
+    /**
+     * vCard 4.0.
+     */
+    const VCARD40 = 6;
+
+    /**
+     * The default name for this component.
+     *
+     * This should be 'VCALENDAR' or 'VCARD'.
+     *
+     * @var string
+     */
+    static $defaultName;
+
+    /**
+     * List of properties, and which classes they map to.
+     *
+     * @var array
+     */
+    static $propertyMap = [];
+
+    /**
+     * List of components, along with which classes they map to.
+     *
+     * @var array
+     */
+    static $componentMap = [];
+
+    /**
+     * List of value-types, and which classes they map to.
+     *
+     * @var array
+     */
+    static $valueMap = [];
+
+    /**
+     * Creates a new document.
+     *
+     * We're changing the default behavior slightly here. First, we don't want
+     * to have to specify a name (we already know it), and we want to allow
+     * children to be specified in the first argument.
+     *
+     * But, the default behavior also works.
+     *
+     * So the two sigs:
+     *
+     * new Document(array $children = [], $defaults = true);
+     * new Document(string $name, array $children = [], $defaults = true)
+     *
+     * @return void
+     */
+    function __construct() {
+
+        $args = func_get_args();
+        if (count($args) === 0 || is_array($args[0])) {
+            array_unshift($args, $this, static::$defaultName);
+            call_user_func_array(['parent', '__construct'], $args);
+        } else {
+            array_unshift($args, $this);
+            call_user_func_array(['parent', '__construct'], $args);
+        }
+
+    }
+
+    /**
+     * Returns the current document type.
+     *
+     * @return int
+     */
+    function getDocumentType() {
+
+        return self::UNKNOWN;
+
+    }
+
+    /**
+     * Creates a new component or property.
+     *
+     * If it's a known component, we will automatically call createComponent.
+     * otherwise, we'll assume it's a property and call createProperty instead.
+     *
+     * @param string $name
+     * @param string $arg1,... Unlimited number of args
+     *
+     * @return mixed
+     */
+    function create($name) {
+
+        if (isset(static::$componentMap[strtoupper($name)])) {
+
+            return call_user_func_array([$this, 'createComponent'], func_get_args());
+
+        } else {
+
+            return call_user_func_array([$this, 'createProperty'], func_get_args());
+
+        }
+
+    }
+
+    /**
+     * Creates a new component.
+     *
+     * This method automatically searches for the correct component class, based
+     * on its name.
+     *
+     * You can specify the children either in key=>value syntax, in which case
+     * properties will automatically be created, or you can just pass a list of
+     * Component and Property object.
+     *
+     * By default, a set of sensible values will be added to the component. For
+     * an iCalendar object, this may be something like CALSCALE:GREGORIAN. To
+     * ensure that this does not happen, set $defaults to false.
+     *
+     * @param string $name
+     * @param array $children
+     * @param bool $defaults
+     *
+     * @return Component
+     */
+    function createComponent($name, array $children = null, $defaults = true) {
+
+        $name = strtoupper($name);
+        $class = 'Sabre\\VObject\\Component';
+
+        if (isset(static::$componentMap[$name])) {
+            $class = static::$componentMap[$name];
+        }
+        if (is_null($children)) $children = [];
+        return new $class($this, $name, $children, $defaults);
+
+    }
+
+    /**
+     * Factory method for creating new properties.
+     *
+     * This method automatically searches for the correct property class, based
+     * on its name.
+     *
+     * You can specify the parameters either in key=>value syntax, in which case
+     * parameters will automatically be created, or you can just pass a list of
+     * Parameter objects.
+     *
+     * @param string $name
+     * @param mixed $value
+     * @param array $parameters
+     * @param string $valueType Force a specific valuetype, such as URI or TEXT
+     *
+     * @return Property
+     */
+    function createProperty($name, $value = null, array $parameters = null, $valueType = null) {
+
+        // If there's a . in the name, it means it's prefixed by a groupname.
+        if (($i = strpos($name, '.')) !== false) {
+            $group = substr($name, 0, $i);
+            $name = strtoupper(substr($name, $i + 1));
+        } else {
+            $name = strtoupper($name);
+            $group = null;
+        }
+
+        $class = null;
+
+        if ($valueType) {
+            // The valueType argument comes first to figure out the correct
+            // class.
+            $class = $this->getClassNameForPropertyValue($valueType);
+        }
+
+        if (is_null($class)) {
+            // If a VALUE parameter is supplied, we should use that.
+            if (isset($parameters['VALUE'])) {
+                $class = $this->getClassNameForPropertyValue($parameters['VALUE']);
+                if (is_null($class)) {
+                    throw new InvalidDataException('Unsupported VALUE parameter for ' . $name . ' property. You supplied "' . $parameters['VALUE'] . '"');
+                }
+            }
+            else {
+                $class = $this->getClassNameForPropertyName($name);
+            }
+        }
+        if (is_null($parameters)) $parameters = [];
+
+        return new $class($this, $name, $value, $parameters, $group);
+
+    }
+
+    /**
+     * This method returns a full class-name for a value parameter.
+     *
+     * For instance, DTSTART may have VALUE=DATE. In that case we will look in
+     * our valueMap table and return the appropriate class name.
+     *
+     * This method returns null if we don't have a specialized class.
+     *
+     * @param string $valueParam
+     * @return string|null
+     */
+    function getClassNameForPropertyValue($valueParam) {
+
+        $valueParam = strtoupper($valueParam);
+        if (isset(static::$valueMap[$valueParam])) {
+            return static::$valueMap[$valueParam];
+        }
+
+    }
+
+    /**
+     * Returns the default class for a property name.
+     *
+     * @param string $propertyName
+     *
+     * @return string
+     */
+    function getClassNameForPropertyName($propertyName) {
+
+        if (isset(static::$propertyMap[$propertyName])) {
+            return static::$propertyMap[$propertyName];
+        } else {
+            return 'Sabre\\VObject\\Property\\Unknown';
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/ElementList.php b/vendor/sabre/vobject/lib/ElementList.php
new file mode 100644
index 000000000..959249247
--- /dev/null
+++ b/vendor/sabre/vobject/lib/ElementList.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace Sabre\VObject;
+
+use ArrayIterator;
+use LogicException;
+
+/**
+ * VObject ElementList.
+ *
+ * This class represents a list of elements. Lists are the result of queries,
+ * such as doing $vcalendar->vevent where there's multiple VEVENT objects.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ElementList extends ArrayIterator {
+
+
+    /* {{{ ArrayAccess Interface */
+
+    /**
+     * Sets an item through ArrayAccess.
+     *
+     * @param int $offset
+     * @param mixed $value
+     *
+     * @return void
+     */
+    function offsetSet($offset, $value) {
+
+        throw new LogicException('You can not add new objects to an ElementList');
+
+    }
+
+    /**
+     * Sets an item through ArrayAccess.
+     *
+     * This method just forwards the request to the inner iterator
+     *
+     * @param int $offset
+     *
+     * @return void
+     */
+    function offsetUnset($offset) {
+
+        throw new LogicException('You can not remove objects from an ElementList');
+
+    }
+
+    /* }}} */
+
+}
diff --git a/vendor/sabre/vobject/lib/EofException.php b/vendor/sabre/vobject/lib/EofException.php
new file mode 100644
index 000000000..e9bd55878
--- /dev/null
+++ b/vendor/sabre/vobject/lib/EofException.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * Exception thrown by parser when the end of the stream has been reached,
+ * before this was expected.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class EofException extends ParseException {
+
+}
diff --git a/vendor/sabre/vobject/lib/FreeBusyData.php b/vendor/sabre/vobject/lib/FreeBusyData.php
new file mode 100644
index 000000000..0a6c72bb2
--- /dev/null
+++ b/vendor/sabre/vobject/lib/FreeBusyData.php
@@ -0,0 +1,193 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * FreeBusyData is a helper class that manages freebusy information.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class FreeBusyData {
+
+    /**
+     * Start timestamp
+     *
+     * @var int
+     */
+    protected $start;
+
+    /**
+     * End timestamp
+     *
+     * @var int
+     */
+    protected $end;
+
+    /**
+     * A list of free-busy times.
+     *
+     * @var array
+     */
+    protected $data;
+
+    function __construct($start, $end) {
+
+        $this->start = $start;
+        $this->end = $end;
+        $this->data = [];
+
+        $this->data[] = [
+            'start' => $this->start,
+            'end'   => $this->end,
+            'type'  => 'FREE',
+        ];
+
+    }
+
+    /**
+     * Adds free or busytime to the data.
+     *
+     * @param int $start
+     * @param int $end
+     * @param string $type FREE, BUSY, BUSY-UNAVAILABLE or BUSY-TENTATIVE
+     * @return void
+     */
+    function add($start, $end, $type) {
+
+        if ($start > $this->end || $end < $this->start) {
+
+            // This new data is outside our timerange.
+            return;
+
+        }
+
+        if ($start < $this->start) {
+            // The item starts before our requested time range
+            $start = $this->start;
+        }
+        if ($end > $this->end) {
+            // The item ends after our requested time range
+            $end = $this->end;
+        }
+
+        // Finding out where we need to insert the new item.
+        $currentIndex = 0;
+        while ($start > $this->data[$currentIndex]['end']) {
+            $currentIndex++;
+        }
+
+        // The standard insertion point will be one _after_ the first
+        // overlapping item.
+        $insertStartIndex = $currentIndex + 1;
+
+        $newItem = [
+            'start' => $start,
+            'end'   => $end,
+            'type'  => $type,
+        ];
+
+        $preceedingItem = $this->data[$insertStartIndex - 1];
+        if ($this->data[$insertStartIndex - 1]['start'] === $start) {
+            // The old item starts at the exact same point as the new item.
+            $insertStartIndex--;
+        }
+
+        // Now we know where to insert the item, we need to know where it
+        // starts overlapping with items on the tail end. We need to start
+        // looking one item before the insertStartIndex, because it's possible
+        // that the new item 'sits inside' the previous old item.
+        if ($insertStartIndex > 0) {
+            $currentIndex = $insertStartIndex - 1;
+        } else {
+            $currentIndex = 0;
+        }
+
+        while ($end > $this->data[$currentIndex]['end']) {
+
+            $currentIndex++;
+
+        }
+
+        // What we are about to insert into the array
+        $newItems = [
+            $newItem
+        ];
+
+        // This is the amount of items that are completely overwritten by the
+        // new item.
+        $itemsToDelete = $currentIndex - $insertStartIndex;
+        if ($this->data[$currentIndex]['end'] <= $end) $itemsToDelete++;
+
+        // If itemsToDelete was -1, it means that the newly inserted item is
+        // actually sitting inside an existing one. This means we need to split
+        // the item at the current position in two and insert the new item in
+        // between.
+        if ($itemsToDelete === -1) {
+            $itemsToDelete = 0;
+            if ($newItem['end'] < $preceedingItem['end']) {
+                $newItems[] = [
+                    'start' => $newItem['end'] + 1,
+                    'end'   => $preceedingItem['end'],
+                    'type'  => $preceedingItem['type']
+                ];
+            }
+        }
+
+        array_splice(
+            $this->data,
+            $insertStartIndex,
+            $itemsToDelete,
+            $newItems
+        );
+
+        $doMerge = false;
+        $mergeOffset = $insertStartIndex;
+        $mergeItem = $newItem;
+        $mergeDelete = 1;
+
+        if (isset($this->data[$insertStartIndex - 1])) {
+            // Updating the start time of the previous item.
+            $this->data[$insertStartIndex - 1]['end'] = $start;
+
+            // If the previous and the current are of the same type, we can
+            // merge them into one item.
+            if ($this->data[$insertStartIndex - 1]['type'] === $this->data[$insertStartIndex]['type']) {
+                $doMerge = true;
+                $mergeOffset--;
+                $mergeDelete++;
+                $mergeItem['start'] = $this->data[$insertStartIndex - 1]['start'];
+            }
+        }
+        if (isset($this->data[$insertStartIndex + 1])) {
+            // Updating the start time of the next item.
+            $this->data[$insertStartIndex + 1]['start'] = $end;
+
+            // If the next and the current are of the same type, we can
+            // merge them into one item.
+            if ($this->data[$insertStartIndex + 1]['type'] === $this->data[$insertStartIndex]['type']) {
+                $doMerge = true;
+                $mergeDelete++;
+                $mergeItem['end'] = $this->data[$insertStartIndex + 1]['end'];
+            }
+
+        }
+        if ($doMerge) {
+            array_splice(
+                $this->data,
+                $mergeOffset,
+                $mergeDelete,
+                [$mergeItem]
+            );
+        }
+
+    }
+
+    function getData() {
+
+        return $this->data;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/FreeBusyGenerator.php b/vendor/sabre/vobject/lib/FreeBusyGenerator.php
new file mode 100644
index 000000000..e33621090
--- /dev/null
+++ b/vendor/sabre/vobject/lib/FreeBusyGenerator.php
@@ -0,0 +1,604 @@
+<?php
+
+namespace Sabre\VObject;
+
+use DateTimeInterface;
+use DateTimeImmutable;
+use DateTimeZone;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Recur\EventIterator;
+use Sabre\VObject\Recur\NoInstancesException;
+
+/**
+ * This class helps with generating FREEBUSY reports based on existing sets of
+ * objects.
+ *
+ * It only looks at VEVENT and VFREEBUSY objects from the sourcedata, and
+ * generates a single VFREEBUSY object.
+ *
+ * VFREEBUSY components are described in RFC5545, The rules for what should
+ * go in a single freebusy report is taken from RFC4791, section 7.10.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class FreeBusyGenerator {
+
+    /**
+     * Input objects.
+     *
+     * @var array
+     */
+    protected $objects = [];
+
+    /**
+     * Start of range.
+     *
+     * @var DateTimeInterface|null
+     */
+    protected $start;
+
+    /**
+     * End of range.
+     *
+     * @var DateTimeInterface|null
+     */
+    protected $end;
+
+    /**
+     * VCALENDAR object.
+     *
+     * @var Document
+     */
+    protected $baseObject;
+
+    /**
+     * Reference timezone.
+     *
+     * When we are calculating busy times, and we come across so-called
+     * floating times (times without a timezone), we use the reference timezone
+     * instead.
+     *
+     * This is also used for all-day events.
+     *
+     * This defaults to UTC.
+     *
+     * @var DateTimeZone
+     */
+    protected $timeZone;
+
+    /**
+     * A VAVAILABILITY document.
+     *
+     * If this is set, it's information will be included when calculating
+     * freebusy time.
+     *
+     * @var Document
+     */
+    protected $vavailability;
+
+    /**
+     * Creates the generator.
+     *
+     * Check the setTimeRange and setObjects methods for details about the
+     * arguments.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     * @param mixed $objects
+     * @param DateTimeZone $timeZone
+     */
+    function __construct(DateTimeInterface $start = null, DateTimeInterface $end = null, $objects = null, DateTimeZone $timeZone = null) {
+
+        $this->setTimeRange($start, $end);
+
+        if ($objects) {
+            $this->setObjects($objects);
+        }
+        if (is_null($timeZone)) {
+            $timeZone = new DateTimeZone('UTC');
+        }
+        $this->setTimeZone($timeZone);
+
+    }
+
+    /**
+     * Sets the VCALENDAR object.
+     *
+     * If this is set, it will not be generated for you. You are responsible
+     * for setting things like the METHOD, CALSCALE, VERSION, etc..
+     *
+     * The VFREEBUSY object will be automatically added though.
+     *
+     * @param Document $vcalendar
+     * @return void
+     */
+    function setBaseObject(Document $vcalendar) {
+
+        $this->baseObject = $vcalendar;
+
+    }
+
+    /**
+     * Sets a VAVAILABILITY document.
+     *
+     * @param Document $vcalendar
+     * @return void
+     */
+    function setVAvailability(Document $vcalendar) {
+
+        $this->vavailability = $vcalendar;
+
+    }
+
+    /**
+     * Sets the input objects.
+     *
+     * You must either specify a valendar object as a string, or as the parse
+     * Component.
+     * It's also possible to specify multiple objects as an array.
+     *
+     * @param mixed $objects
+     *
+     * @return void
+     */
+    function setObjects($objects) {
+
+        if (!is_array($objects)) {
+            $objects = [$objects];
+        }
+
+        $this->objects = [];
+        foreach ($objects as $object) {
+
+            if (is_string($object)) {
+                $this->objects[] = Reader::read($object);
+            } elseif ($object instanceof Component) {
+                $this->objects[] = $object;
+            } else {
+                throw new \InvalidArgumentException('You can only pass strings or \\Sabre\\VObject\\Component arguments to setObjects');
+            }
+
+        }
+
+    }
+
+    /**
+     * Sets the time range.
+     *
+     * Any freebusy object falling outside of this time range will be ignored.
+     *
+     * @param DateTimeInterface $start
+     * @param DateTimeInterface $end
+     *
+     * @return void
+     */
+    function setTimeRange(DateTimeInterface $start = null, DateTimeInterface $end = null) {
+
+        if (!$start) {
+            $start = new DateTimeImmutable(Settings::$minDate);
+        }
+        if (!$end) {
+            $end = new DateTimeImmutable(Settings::$maxDate);
+        }
+        $this->start = $start;
+        $this->end = $end;
+
+    }
+
+    /**
+     * Sets the reference timezone for floating times.
+     *
+     * @param DateTimeZone $timeZone
+     *
+     * @return void
+     */
+    function setTimeZone(DateTimeZone $timeZone) {
+
+        $this->timeZone = $timeZone;
+
+    }
+
+    /**
+     * Parses the input data and returns a correct VFREEBUSY object, wrapped in
+     * a VCALENDAR.
+     *
+     * @return Component
+     */
+    function getResult() {
+
+        $fbData = new FreeBusyData(
+            $this->start->getTimeStamp(),
+            $this->end->getTimeStamp()
+        );
+        if ($this->vavailability) {
+
+            $this->calculateAvailability($fbData, $this->vavailability);
+
+        }
+
+        $this->calculateBusy($fbData, $this->objects);
+
+        return $this->generateFreeBusyCalendar($fbData);
+
+
+    }
+
+    /**
+     * This method takes a VAVAILABILITY component and figures out all the
+     * available times.
+     *
+     * @param FreeBusyData $fbData
+     * @param VCalendar $vavailability
+     * @return void
+     */
+    protected function calculateAvailability(FreeBusyData $fbData, VCalendar $vavailability) {
+
+        $vavailComps = iterator_to_array($vavailability->VAVAILABILITY);
+        usort(
+            $vavailComps,
+            function($a, $b) {
+
+                // We need to order the components by priority. Priority 1
+                // comes first, up until priority 9. Priority 0 comes after
+                // priority 9. No priority implies priority 0.
+                //
+                // Yes, I'm serious.
+                $priorityA = isset($a->PRIORITY) ? (int)$a->PRIORITY->getValue() : 0;
+                $priorityB = isset($b->PRIORITY) ? (int)$b->PRIORITY->getValue() : 0;
+
+                if ($priorityA === 0) $priorityA = 10;
+                if ($priorityB === 0) $priorityB = 10;
+
+                return $priorityA - $priorityB;
+
+            }
+        );
+
+        // Now we go over all the VAVAILABILITY components and figure if
+        // there's any we don't need to consider.
+        //
+        // This is can be because of one of two reasons: either the
+        // VAVAILABILITY component falls outside the time we are interested in,
+        // or a different VAVAILABILITY component with a higher priority has
+        // already completely covered the time-range.
+        $old = $vavailComps;
+        $new = [];
+
+        foreach ($old as $vavail) {
+
+            list($compStart, $compEnd) = $vavail->getEffectiveStartEnd();
+
+            // We don't care about datetimes that are earlier or later than the
+            // start and end of the freebusy report, so this gets normalized
+            // first.
+            if (is_null($compStart) || $compStart < $this->start) {
+                $compStart = $this->start;
+            }
+            if (is_null($compEnd) || $compEnd > $this->end) {
+                $compEnd = $this->end;
+            }
+
+            // If the item fell out of the timerange, we can just skip it.
+            if ($compStart > $this->end || $compEnd < $this->start) {
+                continue;
+            }
+
+            // Going through our existing list of components to see if there's
+            // a higher priority component that already fully covers this one.
+            foreach ($new as $higherVavail) {
+
+                list($higherStart, $higherEnd) = $higherVavail->getEffectiveStartEnd();
+                if (
+                    (is_null($higherStart) || $higherStart < $compStart) &&
+                    (is_null($higherEnd)   || $higherEnd > $compEnd)
+                ) {
+
+                    // Component is fully covered by a higher priority
+                    // component. We can skip this component.
+                    continue 2;
+
+                }
+
+            }
+
+            // We're keeping it!
+            $new[] = $vavail;
+
+        }
+
+        // Lastly, we need to traverse the remaining components and fill in the
+        // freebusydata slots.
+        //
+        // We traverse the components in reverse, because we want the higher
+        // priority components to override the lower ones.
+        foreach (array_reverse($new) as $vavail) {
+
+            $busyType = isset($vavail->BUSYTYPE) ? strtoupper($vavail->BUSYTYPE) : 'BUSY-UNAVAILABLE';
+            list($vavailStart, $vavailEnd) = $vavail->getEffectiveStartEnd();
+
+            // Making the component size no larger than the requested free-busy
+            // report range.
+            if (!$vavailStart || $vavailStart < $this->start) {
+                $vavailStart = $this->start;
+            }
+            if (!$vavailEnd || $vavailEnd > $this->end) {
+                $vavailEnd = $this->end;
+            }
+
+            // Marking the entire time range of the VAVAILABILITY component as
+            // busy.
+            $fbData->add(
+                $vavailStart->getTimeStamp(),
+                $vavailEnd->getTimeStamp(),
+                $busyType
+            );
+
+            // Looping over the AVAILABLE components.
+            if (isset($vavail->AVAILABLE)) foreach ($vavail->AVAILABLE as $available) {
+
+                list($availStart, $availEnd) = $available->getEffectiveStartEnd();
+                $fbData->add(
+                    $availStart->getTimeStamp(),
+                    $availEnd->getTimeStamp(),
+                    'FREE'
+                );
+
+                if ($available->RRULE) {
+                    // Our favourite thing: recurrence!!
+
+                    $rruleIterator = new Recur\RRuleIterator(
+                        $available->RRULE->getValue(),
+                        $availStart
+                    );
+                    $rruleIterator->fastForward($vavailStart);
+
+                    $startEndDiff = $availStart->diff($availEnd);
+
+                    while ($rruleIterator->valid()) {
+
+                        $recurStart = $rruleIterator->current();
+                        $recurEnd = $recurStart->add($startEndDiff);
+
+                        if ($recurStart > $vavailEnd) {
+                            // We're beyond the legal timerange.
+                            break;
+                        }
+
+                        if ($recurEnd > $vavailEnd) {
+                            // Truncating the end if it exceeds the
+                            // VAVAILABILITY end.
+                            $recurEnd = $vavailEnd;
+                        }
+
+                        $fbData->add(
+                            $recurStart->getTimeStamp(),
+                            $recurEnd->getTimeStamp(),
+                            'FREE'
+                        );
+
+                        $rruleIterator->next();
+
+                    }
+                }
+
+            }
+
+        }
+
+    }
+
+    /**
+     * This method takes an array of iCalendar objects and applies its busy
+     * times on fbData.
+     *
+     * @param FreeBusyData $fbData
+     * @param VCalendar[] $objects
+     */
+    protected function calculateBusy(FreeBusyData $fbData, array $objects) {
+
+        foreach ($objects as $key => $object) {
+
+            foreach ($object->getBaseComponents() as $component) {
+
+                switch ($component->name) {
+
+                    case 'VEVENT' :
+
+                        $FBTYPE = 'BUSY';
+                        if (isset($component->TRANSP) && (strtoupper($component->TRANSP) === 'TRANSPARENT')) {
+                            break;
+                        }
+                        if (isset($component->STATUS)) {
+                            $status = strtoupper($component->STATUS);
+                            if ($status === 'CANCELLED') {
+                                break;
+                            }
+                            if ($status === 'TENTATIVE') {
+                                $FBTYPE = 'BUSY-TENTATIVE';
+                            }
+                        }
+
+                        $times = [];
+
+                        if ($component->RRULE) {
+                            try {
+                                $iterator = new EventIterator($object, (string)$component->UID, $this->timeZone);
+                            } catch (NoInstancesException $e) {
+                                // This event is recurring, but it doesn't have a single
+                                // instance. We are skipping this event from the output
+                                // entirely.
+                                unset($this->objects[$key]);
+                                continue;
+                            }
+
+                            if ($this->start) {
+                                $iterator->fastForward($this->start);
+                            }
+
+                            $maxRecurrences = Settings::$maxRecurrences;
+
+                            while ($iterator->valid() && --$maxRecurrences) {
+
+                                $startTime = $iterator->getDTStart();
+                                if ($this->end && $startTime > $this->end) {
+                                    break;
+                                }
+                                $times[] = [
+                                    $iterator->getDTStart(),
+                                    $iterator->getDTEnd(),
+                                ];
+
+                                $iterator->next();
+
+                            }
+
+                        } else {
+
+                            $startTime = $component->DTSTART->getDateTime($this->timeZone);
+                            if ($this->end && $startTime > $this->end) {
+                                break;
+                            }
+                            $endTime = null;
+                            if (isset($component->DTEND)) {
+                                $endTime = $component->DTEND->getDateTime($this->timeZone);
+                            } elseif (isset($component->DURATION)) {
+                                $duration = DateTimeParser::parseDuration((string)$component->DURATION);
+                                $endTime = clone $startTime;
+                                $endTime = $endTime->add($duration);
+                            } elseif (!$component->DTSTART->hasTime()) {
+                                $endTime = clone $startTime;
+                                $endTime = $endTime->modify('+1 day');
+                            } else {
+                                // The event had no duration (0 seconds)
+                                break;
+                            }
+
+                            $times[] = [$startTime, $endTime];
+
+                        }
+
+                        foreach ($times as $time) {
+
+                            if ($this->end && $time[0] > $this->end) break;
+                            if ($this->start && $time[1] < $this->start) break;
+
+                            $fbData->add(
+                                $time[0]->getTimeStamp(),
+                                $time[1]->getTimeStamp(),
+                                $FBTYPE
+                            );
+                        }
+                        break;
+
+                    case 'VFREEBUSY' :
+                        foreach ($component->FREEBUSY as $freebusy) {
+
+                            $fbType = isset($freebusy['FBTYPE']) ? strtoupper($freebusy['FBTYPE']) : 'BUSY';
+
+                            // Skipping intervals marked as 'free'
+                            if ($fbType === 'FREE')
+                                continue;
+
+                            $values = explode(',', $freebusy);
+                            foreach ($values as $value) {
+                                list($startTime, $endTime) = explode('/', $value);
+                                $startTime = DateTimeParser::parseDateTime($startTime);
+
+                                if (substr($endTime, 0, 1) === 'P' || substr($endTime, 0, 2) === '-P') {
+                                    $duration = DateTimeParser::parseDuration($endTime);
+                                    $endTime = clone $startTime;
+                                    $endTime = $endTime->add($duration);
+                                } else {
+                                    $endTime = DateTimeParser::parseDateTime($endTime);
+                                }
+
+                                if ($this->start && $this->start > $endTime) continue;
+                                if ($this->end && $this->end < $startTime) continue;
+                                $fbData->add(
+                                    $startTime->getTimeStamp(),
+                                    $endTime->getTimeStamp(),
+                                    $fbType
+                                );
+
+                            }
+
+
+                        }
+                        break;
+
+                }
+
+
+            }
+
+        }
+
+    }
+
+    /**
+     * This method takes a FreeBusyData object and generates the VCALENDAR
+     * object associated with it.
+     *
+     * @return VCalendar
+     */
+    protected function generateFreeBusyCalendar(FreeBusyData $fbData) {
+
+        if ($this->baseObject) {
+            $calendar = $this->baseObject;
+        } else {
+            $calendar = new VCalendar();
+        }
+
+        $vfreebusy = $calendar->createComponent('VFREEBUSY');
+        $calendar->add($vfreebusy);
+
+        if ($this->start) {
+            $dtstart = $calendar->createProperty('DTSTART');
+            $dtstart->setDateTime($this->start);
+            $vfreebusy->add($dtstart);
+        }
+        if ($this->end) {
+            $dtend = $calendar->createProperty('DTEND');
+            $dtend->setDateTime($this->end);
+            $vfreebusy->add($dtend);
+        }
+
+        $tz = new \DateTimeZone('UTC');
+        $dtstamp = $calendar->createProperty('DTSTAMP');
+        $dtstamp->setDateTime(new DateTimeImmutable('now', $tz));
+        $vfreebusy->add($dtstamp);
+
+        foreach ($fbData->getData() as $busyTime) {
+
+            $busyType = strtoupper($busyTime['type']);
+
+            // Ignoring all the FREE parts, because those are already assumed.
+            if ($busyType === 'FREE') {
+                continue;
+            }
+
+            $busyTime[0] = new \DateTimeImmutable('@' . $busyTime['start'], $tz);
+            $busyTime[1] = new \DateTimeImmutable('@' . $busyTime['end'], $tz);
+
+            $prop = $calendar->createProperty(
+                'FREEBUSY',
+                $busyTime[0]->format('Ymd\\THis\\Z') . '/' . $busyTime[1]->format('Ymd\\THis\\Z')
+            );
+
+            // Only setting FBTYPE if it's not BUSY, because BUSY is the
+            // default anyway.
+            if ($busyType !== 'BUSY') {
+                $prop['FBTYPE'] = $busyType;
+            }
+            $vfreebusy->add($prop);
+
+        }
+
+        return $calendar;
+
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/ITip/Broker.php b/vendor/sabre/vobject/lib/ITip/Broker.php
new file mode 100644
index 000000000..effa74317
--- /dev/null
+++ b/vendor/sabre/vobject/lib/ITip/Broker.php
@@ -0,0 +1,989 @@
+<?php
+
+namespace Sabre\VObject\ITip;
+
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\Reader;
+use Sabre\VObject\Recur\EventIterator;
+
+/**
+ * The ITip\Broker class is a utility class that helps with processing
+ * so-called iTip messages.
+ *
+ * iTip is defined in rfc5546, stands for iCalendar Transport-Independent
+ * Interoperability Protocol, and describes the underlying mechanism for
+ * using iCalendar for scheduling for for example through email (also known as
+ * IMip) and CalDAV Scheduling.
+ *
+ * This class helps by:
+ *
+ * 1. Creating individual invites based on an iCalendar event for each
+ *    attendee.
+ * 2. Generating invite updates based on an iCalendar update. This may result
+ *    in new invites, updates and cancellations for attendees, if that list
+ *    changed.
+ * 3. On the receiving end, it can create a local iCalendar event based on
+ *    a received invite.
+ * 4. It can also process an invite update on a local event, ensuring that any
+ *    overridden properties from attendees are retained.
+ * 5. It can create a accepted or declined iTip reply based on an invite.
+ * 6. It can process a reply from an invite and update an events attendee
+ *     status based on a reply.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Broker {
+
+    /**
+     * This setting determines whether the rules for the SCHEDULE-AGENT
+     * parameter should be followed.
+     *
+     * This is a parameter defined on ATTENDEE properties, introduced by RFC
+     * 6638. This parameter allows a caldav client to tell the server 'Don't do
+     * any scheduling operations'.
+     *
+     * If this setting is turned on, any attendees with SCHEDULE-AGENT set to
+     * CLIENT will be ignored. This is the desired behavior for a CalDAV
+     * server, but if you're writing an iTip application that doesn't deal with
+     * CalDAV, you may want to ignore this parameter.
+     *
+     * @var bool
+     */
+    public $scheduleAgentServerRules = true;
+
+    /**
+     * The broker will try during 'parseEvent' figure out whether the change
+     * was significant.
+     *
+     * It uses a few different ways to do this. One of these ways is seeing if
+     * certain properties changed values. This list of specified here.
+     *
+     * This list is taken from:
+     * * http://tools.ietf.org/html/rfc5546#section-2.1.4
+     *
+     * @var string[]
+     */
+    public $significantChangeProperties = [
+        'DTSTART',
+        'DTEND',
+        'DURATION',
+        'DUE',
+        'RRULE',
+        'RDATE',
+        'EXDATE',
+        'STATUS',
+    ];
+
+    /**
+     * This method is used to process an incoming itip message.
+     *
+     * Examples:
+     *
+     * 1. A user is an attendee to an event. The organizer sends an updated
+     * meeting using a new iTip message with METHOD:REQUEST. This function
+     * will process the message and update the attendee's event accordingly.
+     *
+     * 2. The organizer cancelled the event using METHOD:CANCEL. We will update
+     * the users event to state STATUS:CANCELLED.
+     *
+     * 3. An attendee sent a reply to an invite using METHOD:REPLY. We can
+     * update the organizers event to update the ATTENDEE with its correct
+     * PARTSTAT.
+     *
+     * The $existingObject is updated in-place. If there is no existing object
+     * (because it's a new invite for example) a new object will be created.
+     *
+     * If an existing object does not exist, and the method was CANCEL or
+     * REPLY, the message effectively gets ignored, and no 'existingObject'
+     * will be created.
+     *
+     * The updated $existingObject is also returned from this function.
+     *
+     * If the iTip message was not supported, we will always return false.
+     *
+     * @param Message $itipMessage
+     * @param VCalendar $existingObject
+     *
+     * @return VCalendar|null
+     */
+    function processMessage(Message $itipMessage, VCalendar $existingObject = null) {
+
+        // We only support events at the moment.
+        if ($itipMessage->component !== 'VEVENT') {
+            return false;
+        }
+
+        switch ($itipMessage->method) {
+
+            case 'REQUEST' :
+                return $this->processMessageRequest($itipMessage, $existingObject);
+
+            case 'CANCEL' :
+                return $this->processMessageCancel($itipMessage, $existingObject);
+
+            case 'REPLY' :
+                return $this->processMessageReply($itipMessage, $existingObject);
+
+            default :
+                // Unsupported iTip message
+                return;
+
+        }
+
+        return $existingObject;
+
+    }
+
+    /**
+     * This function parses a VCALENDAR object and figure out if any messages
+     * need to be sent.
+     *
+     * A VCALENDAR object will be created from the perspective of either an
+     * attendee, or an organizer. You must pass a string identifying the
+     * current user, so we can figure out who in the list of attendees or the
+     * organizer we are sending this message on behalf of.
+     *
+     * It's possible to specify the current user as an array, in case the user
+     * has more than one identifying href (such as multiple emails).
+     *
+     * It $oldCalendar is specified, it is assumed that the operation is
+     * updating an existing event, which means that we need to look at the
+     * differences between events, and potentially send old attendees
+     * cancellations, and current attendees updates.
+     *
+     * If $calendar is null, but $oldCalendar is specified, we treat the
+     * operation as if the user has deleted an event. If the user was an
+     * organizer, this means that we need to send cancellation notices to
+     * people. If the user was an attendee, we need to make sure that the
+     * organizer gets the 'declined' message.
+     *
+     * @param VCalendar|string $calendar
+     * @param string|array $userHref
+     * @param VCalendar|string $oldCalendar
+     *
+     * @return array
+     */
+    function parseEvent($calendar = null, $userHref, $oldCalendar = null) {
+
+        if ($oldCalendar) {
+            if (is_string($oldCalendar)) {
+                $oldCalendar = Reader::read($oldCalendar);
+            }
+            if (!isset($oldCalendar->VEVENT)) {
+                // We only support events at the moment
+                return [];
+            }
+
+            $oldEventInfo = $this->parseEventInfo($oldCalendar);
+        } else {
+            $oldEventInfo = [
+                'organizer'             => null,
+                'significantChangeHash' => '',
+                'attendees'             => [],
+            ];
+        }
+
+        $userHref = (array)$userHref;
+
+        if (!is_null($calendar)) {
+
+            if (is_string($calendar)) {
+                $calendar = Reader::read($calendar);
+            }
+            if (!isset($calendar->VEVENT)) {
+                // We only support events at the moment
+                return [];
+            }
+            $eventInfo = $this->parseEventInfo($calendar);
+            if (!$eventInfo['attendees'] && !$oldEventInfo['attendees']) {
+                // If there were no attendees on either side of the equation,
+                // we don't need to do anything.
+                return [];
+            }
+            if (!$eventInfo['organizer'] && !$oldEventInfo['organizer']) {
+                // There was no organizer before or after the change.
+                return [];
+            }
+
+            $baseCalendar = $calendar;
+
+            // If the new object didn't have an organizer, the organizer
+            // changed the object from a scheduling object to a non-scheduling
+            // object. We just copy the info from the old object.
+            if (!$eventInfo['organizer'] && $oldEventInfo['organizer']) {
+                $eventInfo['organizer'] = $oldEventInfo['organizer'];
+                $eventInfo['organizerName'] = $oldEventInfo['organizerName'];
+            }
+
+        } else {
+            // The calendar object got deleted, we need to process this as a
+            // cancellation / decline.
+            if (!$oldCalendar) {
+                // No old and no new calendar, there's no thing to do.
+                return [];
+            }
+
+            $eventInfo = $oldEventInfo;
+
+            if (in_array($eventInfo['organizer'], $userHref)) {
+                // This is an organizer deleting the event.
+                $eventInfo['attendees'] = [];
+                // Increasing the sequence, but only if the organizer deleted
+                // the event.
+                $eventInfo['sequence']++;
+            } else {
+                // This is an attendee deleting the event.
+                foreach ($eventInfo['attendees'] as $key => $attendee) {
+                    if (in_array($attendee['href'], $userHref)) {
+                        $eventInfo['attendees'][$key]['instances'] = ['master' =>
+                            ['id' => 'master', 'partstat' => 'DECLINED']
+                        ];
+                    }
+                }
+            }
+            $baseCalendar = $oldCalendar;
+
+        }
+
+        if (in_array($eventInfo['organizer'], $userHref)) {
+            return $this->parseEventForOrganizer($baseCalendar, $eventInfo, $oldEventInfo);
+        } elseif ($oldCalendar) {
+            // We need to figure out if the user is an attendee, but we're only
+            // doing so if there's an oldCalendar, because we only want to
+            // process updates, not creation of new events.
+            foreach ($eventInfo['attendees'] as $attendee) {
+                if (in_array($attendee['href'], $userHref)) {
+                    return $this->parseEventForAttendee($baseCalendar, $eventInfo, $oldEventInfo, $attendee['href']);
+                }
+            }
+        }
+        return [];
+
+    }
+
+    /**
+     * Processes incoming REQUEST messages.
+     *
+     * This is message from an organizer, and is either a new event
+     * invite, or an update to an existing one.
+     *
+     *
+     * @param Message $itipMessage
+     * @param VCalendar $existingObject
+     *
+     * @return VCalendar|null
+     */
+    protected function processMessageRequest(Message $itipMessage, VCalendar $existingObject = null) {
+
+        if (!$existingObject) {
+            // This is a new invite, and we're just going to copy over
+            // all the components from the invite.
+            $existingObject = new VCalendar();
+            foreach ($itipMessage->message->getComponents() as $component) {
+                $existingObject->add(clone $component);
+            }
+        } else {
+            // We need to update an existing object with all the new
+            // information. We can just remove all existing components
+            // and create new ones.
+            foreach ($existingObject->getComponents() as $component) {
+                $existingObject->remove($component);
+            }
+            foreach ($itipMessage->message->getComponents() as $component) {
+                $existingObject->add(clone $component);
+            }
+        }
+        return $existingObject;
+
+    }
+
+    /**
+     * Processes incoming CANCEL messages.
+     *
+     * This is a message from an organizer, and means that either an
+     * attendee got removed from an event, or an event got cancelled
+     * altogether.
+     *
+     * @param Message $itipMessage
+     * @param VCalendar $existingObject
+     *
+     * @return VCalendar|null
+     */
+    protected function processMessageCancel(Message $itipMessage, VCalendar $existingObject = null) {
+
+        if (!$existingObject) {
+            // The event didn't exist in the first place, so we're just
+            // ignoring this message.
+        } else {
+            foreach ($existingObject->VEVENT as $vevent) {
+                $vevent->STATUS = 'CANCELLED';
+                $vevent->SEQUENCE = $itipMessage->sequence;
+            }
+        }
+        return $existingObject;
+
+    }
+
+    /**
+     * Processes incoming REPLY messages.
+     *
+     * The message is a reply. This is for example an attendee telling
+     * an organizer he accepted the invite, or declined it.
+     *
+     * @param Message $itipMessage
+     * @param VCalendar $existingObject
+     *
+     * @return VCalendar|null
+     */
+    protected function processMessageReply(Message $itipMessage, VCalendar $existingObject = null) {
+
+        // A reply can only be processed based on an existing object.
+        // If the object is not available, the reply is ignored.
+        if (!$existingObject) {
+            return;
+        }
+        $instances = [];
+        $requestStatus = '2.0';
+
+        // Finding all the instances the attendee replied to.
+        foreach ($itipMessage->message->VEVENT as $vevent) {
+            $recurId = isset($vevent->{'RECURRENCE-ID'}) ? $vevent->{'RECURRENCE-ID'}->getValue() : 'master';
+            $attendee = $vevent->ATTENDEE;
+            $instances[$recurId] = $attendee['PARTSTAT']->getValue();
+            if (isset($vevent->{'REQUEST-STATUS'})) {
+                $requestStatus = $vevent->{'REQUEST-STATUS'}->getValue();
+                list($requestStatus) = explode(';', $requestStatus);
+            }
+        }
+
+        // Now we need to loop through the original organizer event, to find
+        // all the instances where we have a reply for.
+        $masterObject = null;
+        foreach ($existingObject->VEVENT as $vevent) {
+            $recurId = isset($vevent->{'RECURRENCE-ID'}) ? $vevent->{'RECURRENCE-ID'}->getValue() : 'master';
+            if ($recurId === 'master') {
+                $masterObject = $vevent;
+            }
+            if (isset($instances[$recurId])) {
+                $attendeeFound = false;
+                if (isset($vevent->ATTENDEE)) {
+                    foreach ($vevent->ATTENDEE as $attendee) {
+                        if ($attendee->getValue() === $itipMessage->sender) {
+                            $attendeeFound = true;
+                            $attendee['PARTSTAT'] = $instances[$recurId];
+                            $attendee['SCHEDULE-STATUS'] = $requestStatus;
+                            // Un-setting the RSVP status, because we now know
+                            // that the attendee already replied.
+                            unset($attendee['RSVP']);
+                            break;
+                        }
+                    }
+                }
+                if (!$attendeeFound) {
+                    // Adding a new attendee. The iTip documentation calls this
+                    // a party crasher.
+                    $attendee = $vevent->add('ATTENDEE', $itipMessage->sender, [
+                        'PARTSTAT' => $instances[$recurId]
+                    ]);
+                    if ($itipMessage->senderName) $attendee['CN'] = $itipMessage->senderName;
+                }
+                unset($instances[$recurId]);
+            }
+        }
+
+        if (!$masterObject) {
+            // No master object, we can't add new instances.
+            return;
+        }
+        // If we got replies to instances that did not exist in the
+        // original list, it means that new exceptions must be created.
+        foreach ($instances as $recurId => $partstat) {
+
+            $recurrenceIterator = new EventIterator($existingObject, $itipMessage->uid);
+            $found = false;
+            $iterations = 1000;
+            do {
+
+                $newObject = $recurrenceIterator->getEventObject();
+                $recurrenceIterator->next();
+
+                if (isset($newObject->{'RECURRENCE-ID'}) && $newObject->{'RECURRENCE-ID'}->getValue() === $recurId) {
+                    $found = true;
+                }
+                $iterations--;
+
+            } while ($recurrenceIterator->valid() && !$found && $iterations);
+
+            // Invalid recurrence id. Skipping this object.
+            if (!$found) continue;
+
+            unset(
+                $newObject->RRULE,
+                $newObject->EXDATE,
+                $newObject->RDATE
+            );
+            $attendeeFound = false;
+            if (isset($newObject->ATTENDEE)) {
+                foreach ($newObject->ATTENDEE as $attendee) {
+                    if ($attendee->getValue() === $itipMessage->sender) {
+                        $attendeeFound = true;
+                        $attendee['PARTSTAT'] = $partstat;
+                        break;
+                    }
+                }
+            }
+            if (!$attendeeFound) {
+                // Adding a new attendee
+                $attendee = $newObject->add('ATTENDEE', $itipMessage->sender, [
+                    'PARTSTAT' => $partstat
+                ]);
+                if ($itipMessage->senderName) {
+                    $attendee['CN'] = $itipMessage->senderName;
+                }
+            }
+            $existingObject->add($newObject);
+
+        }
+        return $existingObject;
+
+    }
+
+    /**
+     * This method is used in cases where an event got updated, and we
+     * potentially need to send emails to attendees to let them know of updates
+     * in the events.
+     *
+     * We will detect which attendees got added, which got removed and create
+     * specific messages for these situations.
+     *
+     * @param VCalendar $calendar
+     * @param array $eventInfo
+     * @param array $oldEventInfo
+     *
+     * @return array
+     */
+    protected function parseEventForOrganizer(VCalendar $calendar, array $eventInfo, array $oldEventInfo) {
+
+        // Merging attendee lists.
+        $attendees = [];
+        foreach ($oldEventInfo['attendees'] as $attendee) {
+            $attendees[$attendee['href']] = [
+                'href'         => $attendee['href'],
+                'oldInstances' => $attendee['instances'],
+                'newInstances' => [],
+                'name'         => $attendee['name'],
+                'forceSend'    => null,
+            ];
+        }
+        foreach ($eventInfo['attendees'] as $attendee) {
+            if (isset($attendees[$attendee['href']])) {
+                $attendees[$attendee['href']]['name'] = $attendee['name'];
+                $attendees[$attendee['href']]['newInstances'] = $attendee['instances'];
+                $attendees[$attendee['href']]['forceSend'] = $attendee['forceSend'];
+            } else {
+                $attendees[$attendee['href']] = [
+                    'href'         => $attendee['href'],
+                    'oldInstances' => [],
+                    'newInstances' => $attendee['instances'],
+                    'name'         => $attendee['name'],
+                    'forceSend'    => $attendee['forceSend'],
+                ];
+            }
+        }
+
+        $messages = [];
+
+        foreach ($attendees as $attendee) {
+
+            // An organizer can also be an attendee. We should not generate any
+            // messages for those.
+            if ($attendee['href'] === $eventInfo['organizer']) {
+                continue;
+            }
+
+            $message = new Message();
+            $message->uid = $eventInfo['uid'];
+            $message->component = 'VEVENT';
+            $message->sequence = $eventInfo['sequence'];
+            $message->sender = $eventInfo['organizer'];
+            $message->senderName = $eventInfo['organizerName'];
+            $message->recipient = $attendee['href'];
+            $message->recipientName = $attendee['name'];
+
+            if (!$attendee['newInstances']) {
+
+                // If there are no instances the attendee is a part of, it
+                // means the attendee was removed and we need to send him a
+                // CANCEL.
+                $message->method = 'CANCEL';
+
+                // Creating the new iCalendar body.
+                $icalMsg = new VCalendar();
+                $icalMsg->METHOD = $message->method;
+                $event = $icalMsg->add('VEVENT', [
+                    'UID'      => $message->uid,
+                    'SEQUENCE' => $message->sequence,
+                ]);
+                if (isset($calendar->VEVENT->SUMMARY)) {
+                    $event->add('SUMMARY', $calendar->VEVENT->SUMMARY->getValue());
+                }
+                $event->add(clone $calendar->VEVENT->DTSTART);
+                if (isset($calendar->VEVENT->DTEND)) {
+                    $event->add(clone $calendar->VEVENT->DTEND);
+                } elseif (isset($calendar->VEVENT->DURATION)) {
+                    $event->add(clone $calendar->VEVENT->DURATION);
+                }
+                $org = $event->add('ORGANIZER', $eventInfo['organizer']);
+                if ($eventInfo['organizerName']) $org['CN'] = $eventInfo['organizerName'];
+                $event->add('ATTENDEE', $attendee['href'], [
+                    'CN' => $attendee['name'],
+                ]);
+                $message->significantChange = true;
+
+            } else {
+
+                // The attendee gets the updated event body
+                $message->method = 'REQUEST';
+
+                // Creating the new iCalendar body.
+                $icalMsg = new VCalendar();
+                $icalMsg->METHOD = $message->method;
+
+                foreach ($calendar->select('VTIMEZONE') as $timezone) {
+                    $icalMsg->add(clone $timezone);
+                }
+
+                // We need to find out that this change is significant. If it's
+                // not, systems may opt to not send messages.
+                //
+                // We do this based on the 'significantChangeHash' which is
+                // some value that changes if there's a certain set of
+                // properties changed in the event, or simply if there's a
+                // difference in instances that the attendee is invited to.
+
+                $message->significantChange =
+                    $attendee['forceSend'] === 'REQUEST' ||
+                    array_keys($attendee['oldInstances']) != array_keys($attendee['newInstances']) ||
+                    $oldEventInfo['significantChangeHash'] !== $eventInfo['significantChangeHash'];
+
+                foreach ($attendee['newInstances'] as $instanceId => $instanceInfo) {
+
+                    $currentEvent = clone $eventInfo['instances'][$instanceId];
+                    if ($instanceId === 'master') {
+
+                        // We need to find a list of events that the attendee
+                        // is not a part of to add to the list of exceptions.
+                        $exceptions = [];
+                        foreach ($eventInfo['instances'] as $instanceId => $vevent) {
+                            if (!isset($attendee['newInstances'][$instanceId])) {
+                                $exceptions[] = $instanceId;
+                            }
+                        }
+
+                        // If there were exceptions, we need to add it to an
+                        // existing EXDATE property, if it exists.
+                        if ($exceptions) {
+                            if (isset($currentEvent->EXDATE)) {
+                                $currentEvent->EXDATE->setParts(array_merge(
+                                    $currentEvent->EXDATE->getParts(),
+                                    $exceptions
+                                ));
+                            } else {
+                                $currentEvent->EXDATE = $exceptions;
+                            }
+                        }
+
+                        // Cleaning up any scheduling information that
+                        // shouldn't be sent along.
+                        unset($currentEvent->ORGANIZER['SCHEDULE-FORCE-SEND']);
+                        unset($currentEvent->ORGANIZER['SCHEDULE-STATUS']);
+
+                        foreach ($currentEvent->ATTENDEE as $attendee) {
+                            unset($attendee['SCHEDULE-FORCE-SEND']);
+                            unset($attendee['SCHEDULE-STATUS']);
+
+                            // We're adding PARTSTAT=NEEDS-ACTION to ensure that
+                            // iOS shows an "Inbox Item"
+                            if (!isset($attendee['PARTSTAT'])) {
+                                $attendee['PARTSTAT'] = 'NEEDS-ACTION';
+                            }
+
+                        }
+
+                    }
+
+                    $icalMsg->add($currentEvent);
+
+                }
+
+            }
+
+            $message->message = $icalMsg;
+            $messages[] = $message;
+
+        }
+
+        return $messages;
+
+    }
+
+    /**
+     * Parse an event update for an attendee.
+     *
+     * This function figures out if we need to send a reply to an organizer.
+     *
+     * @param VCalendar $calendar
+     * @param array $eventInfo
+     * @param array $oldEventInfo
+     * @param string $attendee
+     *
+     * @return Message[]
+     */
+    protected function parseEventForAttendee(VCalendar $calendar, array $eventInfo, array $oldEventInfo, $attendee) {
+
+        if ($this->scheduleAgentServerRules && $eventInfo['organizerScheduleAgent'] === 'CLIENT') {
+            return [];
+        }
+
+        // Don't bother generating messages for events that have already been
+        // cancelled.
+        if ($eventInfo['status'] === 'CANCELLED') {
+            return [];
+        }
+
+        $oldInstances = !empty($oldEventInfo['attendees'][$attendee]['instances']) ?
+            $oldEventInfo['attendees'][$attendee]['instances'] :
+            [];
+
+        $instances = [];
+        foreach ($oldInstances as $instance) {
+
+            $instances[$instance['id']] = [
+                'id'        => $instance['id'],
+                'oldstatus' => $instance['partstat'],
+                'newstatus' => null,
+            ];
+
+        }
+        foreach ($eventInfo['attendees'][$attendee]['instances'] as $instance) {
+
+            if (isset($instances[$instance['id']])) {
+                $instances[$instance['id']]['newstatus'] = $instance['partstat'];
+            } else {
+                $instances[$instance['id']] = [
+                    'id'        => $instance['id'],
+                    'oldstatus' => null,
+                    'newstatus' => $instance['partstat'],
+                ];
+            }
+
+        }
+
+        // We need to also look for differences in EXDATE. If there are new
+        // items in EXDATE, it means that an attendee deleted instances of an
+        // event, which means we need to send DECLINED specifically for those
+        // instances.
+        // We only need to do that though, if the master event is not declined.
+        if (isset($instances['master']) && $instances['master']['newstatus'] !== 'DECLINED') {
+            foreach ($eventInfo['exdate'] as $exDate) {
+
+                if (!in_array($exDate, $oldEventInfo['exdate'])) {
+                    if (isset($instances[$exDate])) {
+                        $instances[$exDate]['newstatus'] = 'DECLINED';
+                    } else {
+                        $instances[$exDate] = [
+                            'id'        => $exDate,
+                            'oldstatus' => null,
+                            'newstatus' => 'DECLINED',
+                        ];
+                    }
+                }
+
+            }
+        }
+
+        // Gathering a few extra properties for each instance.
+        foreach ($instances as $recurId => $instanceInfo) {
+
+            if (isset($eventInfo['instances'][$recurId])) {
+                $instances[$recurId]['dtstart'] = clone $eventInfo['instances'][$recurId]->DTSTART;
+            } else {
+                $instances[$recurId]['dtstart'] = $recurId;
+            }
+
+        }
+
+        $message = new Message();
+        $message->uid = $eventInfo['uid'];
+        $message->method = 'REPLY';
+        $message->component = 'VEVENT';
+        $message->sequence = $eventInfo['sequence'];
+        $message->sender = $attendee;
+        $message->senderName = $eventInfo['attendees'][$attendee]['name'];
+        $message->recipient = $eventInfo['organizer'];
+        $message->recipientName = $eventInfo['organizerName'];
+
+        $icalMsg = new VCalendar();
+        $icalMsg->METHOD = 'REPLY';
+
+        $hasReply = false;
+
+        foreach ($instances as $instance) {
+
+            if ($instance['oldstatus'] == $instance['newstatus'] && $eventInfo['organizerForceSend'] !== 'REPLY') {
+                // Skip
+                continue;
+            }
+
+            $event = $icalMsg->add('VEVENT', [
+                'UID'      => $message->uid,
+                'SEQUENCE' => $message->sequence,
+            ]);
+            $summary = isset($calendar->VEVENT->SUMMARY) ? $calendar->VEVENT->SUMMARY->getValue() : '';
+            // Adding properties from the correct source instance
+            if (isset($eventInfo['instances'][$instance['id']])) {
+                $instanceObj = $eventInfo['instances'][$instance['id']];
+                $event->add(clone $instanceObj->DTSTART);
+                if (isset($instanceObj->DTEND)) {
+                    $event->add(clone $instanceObj->DTEND);
+                } elseif (isset($instanceObj->DURATION)) {
+                    $event->add(clone $instanceObj->DURATION);
+                }
+                if (isset($instanceObj->SUMMARY)) {
+                    $event->add('SUMMARY', $instanceObj->SUMMARY->getValue());
+                } elseif ($summary) {
+                    $event->add('SUMMARY', $summary);
+                }
+            } else {
+                // This branch of the code is reached, when a reply is
+                // generated for an instance of a recurring event, through the
+                // fact that the instance has disappeared by showing up in
+                // EXDATE
+                $dt = DateTimeParser::parse($instance['id'], $eventInfo['timezone']);
+                // Treat is as a DATE field
+                if (strlen($instance['id']) <= 8) {
+                    $event->add('DTSTART', $dt, ['VALUE' => 'DATE']);
+                } else {
+                    $event->add('DTSTART', $dt);
+                }
+                if ($summary) {
+                    $event->add('SUMMARY', $summary);
+                }
+            }
+            if ($instance['id'] !== 'master') {
+                $dt = DateTimeParser::parse($instance['id'], $eventInfo['timezone']);
+                // Treat is as a DATE field
+                if (strlen($instance['id']) <= 8) {
+                    $event->add('RECURRENCE-ID', $dt, ['VALUE' => 'DATE']);
+                } else {
+                    $event->add('RECURRENCE-ID', $dt);
+                }
+            }
+            $organizer = $event->add('ORGANIZER', $message->recipient);
+            if ($message->recipientName) {
+                $organizer['CN'] = $message->recipientName;
+            }
+            $attendee = $event->add('ATTENDEE', $message->sender, [
+                'PARTSTAT' => $instance['newstatus']
+            ]);
+            if ($message->senderName) {
+                $attendee['CN'] = $message->senderName;
+            }
+            $hasReply = true;
+
+        }
+
+        if ($hasReply) {
+            $message->message = $icalMsg;
+            return [$message];
+        } else {
+            return [];
+        }
+
+    }
+
+    /**
+     * Returns attendee information and information about instances of an
+     * event.
+     *
+     * Returns an array with the following keys:
+     *
+     * 1. uid
+     * 2. organizer
+     * 3. organizerName
+     * 4. organizerScheduleAgent
+     * 5. organizerForceSend
+     * 6. instances
+     * 7. attendees
+     * 8. sequence
+     * 9. exdate
+     * 10. timezone - strictly the timezone on which the recurrence rule is
+     *                based on.
+     * 11. significantChangeHash
+     * 12. status
+     * @param VCalendar $calendar
+     *
+     * @return array
+     */
+    protected function parseEventInfo(VCalendar $calendar = null) {
+
+        $uid = null;
+        $organizer = null;
+        $organizerName = null;
+        $organizerForceSend = null;
+        $sequence = null;
+        $timezone = null;
+        $status = null;
+        $organizerScheduleAgent = 'SERVER';
+
+        $significantChangeHash = '';
+
+        // Now we need to collect a list of attendees, and which instances they
+        // are a part of.
+        $attendees = [];
+
+        $instances = [];
+        $exdate = [];
+
+        foreach ($calendar->VEVENT as $vevent) {
+
+            if (is_null($uid)) {
+                $uid = $vevent->UID->getValue();
+            } else {
+                if ($uid !== $vevent->UID->getValue()) {
+                    throw new ITipException('If a calendar contained more than one event, they must have the same UID.');
+                }
+            }
+
+            if (!isset($vevent->DTSTART)) {
+                throw new ITipException('An event MUST have a DTSTART property.');
+            }
+
+            if (isset($vevent->ORGANIZER)) {
+                if (is_null($organizer)) {
+                    $organizer = $vevent->ORGANIZER->getNormalizedValue();
+                    $organizerName = isset($vevent->ORGANIZER['CN']) ? $vevent->ORGANIZER['CN'] : null;
+                } else {
+                    if ($organizer !== $vevent->ORGANIZER->getNormalizedValue()) {
+                        throw new SameOrganizerForAllComponentsException('Every instance of the event must have the same organizer.');
+                    }
+                }
+                $organizerForceSend =
+                    isset($vevent->ORGANIZER['SCHEDULE-FORCE-SEND']) ?
+                    strtoupper($vevent->ORGANIZER['SCHEDULE-FORCE-SEND']) :
+                    null;
+                $organizerScheduleAgent =
+                    isset($vevent->ORGANIZER['SCHEDULE-AGENT']) ?
+                    strtoupper((string)$vevent->ORGANIZER['SCHEDULE-AGENT']) :
+                    'SERVER';
+            }
+            if (is_null($sequence) && isset($vevent->SEQUENCE)) {
+                $sequence = $vevent->SEQUENCE->getValue();
+            }
+            if (isset($vevent->EXDATE)) {
+                foreach ($vevent->select('EXDATE') as $val) {
+                    $exdate = array_merge($exdate, $val->getParts());
+                }
+                sort($exdate);
+            }
+            if (isset($vevent->STATUS)) {
+                $status = strtoupper($vevent->STATUS->getValue());
+            }
+
+            $recurId = isset($vevent->{'RECURRENCE-ID'}) ? $vevent->{'RECURRENCE-ID'}->getValue() : 'master';
+            if (is_null($timezone)) {
+                if ($recurId === 'master') {
+                    $timezone = $vevent->DTSTART->getDateTime()->getTimeZone();
+                } else {
+                    $timezone = $vevent->{'RECURRENCE-ID'}->getDateTime()->getTimeZone();
+                }
+            }
+            if (isset($vevent->ATTENDEE)) {
+                foreach ($vevent->ATTENDEE as $attendee) {
+
+                    if ($this->scheduleAgentServerRules &&
+                        isset($attendee['SCHEDULE-AGENT']) &&
+                        strtoupper($attendee['SCHEDULE-AGENT']->getValue()) === 'CLIENT'
+                    ) {
+                        continue;
+                    }
+                    $partStat =
+                        isset($attendee['PARTSTAT']) ?
+                        strtoupper($attendee['PARTSTAT']) :
+                        'NEEDS-ACTION';
+
+                    $forceSend =
+                        isset($attendee['SCHEDULE-FORCE-SEND']) ?
+                        strtoupper($attendee['SCHEDULE-FORCE-SEND']) :
+                        null;
+
+
+                    if (isset($attendees[$attendee->getNormalizedValue()])) {
+                        $attendees[$attendee->getNormalizedValue()]['instances'][$recurId] = [
+                            'id'         => $recurId,
+                            'partstat'   => $partStat,
+                            'force-send' => $forceSend,
+                        ];
+                    } else {
+                        $attendees[$attendee->getNormalizedValue()] = [
+                            'href'      => $attendee->getNormalizedValue(),
+                            'instances' => [
+                                $recurId => [
+                                    'id'       => $recurId,
+                                    'partstat' => $partStat,
+                                ],
+                            ],
+                            'name'      => isset($attendee['CN']) ? (string)$attendee['CN'] : null,
+                            'forceSend' => $forceSend,
+                        ];
+                    }
+
+                }
+                $instances[$recurId] = $vevent;
+
+            }
+
+            foreach ($this->significantChangeProperties as $prop) {
+                if (isset($vevent->$prop)) {
+                    $propertyValues = $vevent->select($prop);
+
+                    $significantChangeHash .= $prop . ':';
+
+                    if ($prop === 'EXDATE') {
+
+                        $significantChangeHash .= implode(',', $exdate) . ';';
+
+                    } else {
+
+                        foreach ($propertyValues as $val) {
+                            $significantChangeHash .= $val->getValue() . ';';
+                        }
+
+                    }
+                }
+            }
+
+        }
+        $significantChangeHash = md5($significantChangeHash);
+
+        return compact(
+            'uid',
+            'organizer',
+            'organizerName',
+            'organizerScheduleAgent',
+            'organizerForceSend',
+            'instances',
+            'attendees',
+            'sequence',
+            'exdate',
+            'timezone',
+            'significantChangeHash',
+            'status'
+        );
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/ITip/ITipException.php b/vendor/sabre/vobject/lib/ITip/ITipException.php
new file mode 100644
index 000000000..ad5e53ab4
--- /dev/null
+++ b/vendor/sabre/vobject/lib/ITip/ITipException.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Sabre\VObject\ITip;
+
+use Exception;
+
+/**
+ * This message is emitted in case of serious problems with iTip messages.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ITipException extends Exception {
+}
diff --git a/vendor/sabre/vobject/lib/ITip/Message.php b/vendor/sabre/vobject/lib/ITip/Message.php
new file mode 100644
index 000000000..bebe2e4fc
--- /dev/null
+++ b/vendor/sabre/vobject/lib/ITip/Message.php
@@ -0,0 +1,141 @@
+<?php
+
+namespace Sabre\VObject\ITip;
+
+/**
+ * This class represents an iTip message.
+ *
+ * A message holds all the information relevant to the message, including the
+ * object itself.
+ *
+ * It should for the most part be treated as immutable.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Message {
+
+    /**
+     * The object's UID.
+     *
+     * @var string
+     */
+    public $uid;
+
+    /**
+     * The component type, such as VEVENT.
+     *
+     * @var string
+     */
+    public $component;
+
+    /**
+     * Contains the ITip method, which is something like REQUEST, REPLY or
+     * CANCEL.
+     *
+     * @var string
+     */
+    public $method;
+
+    /**
+     * The current sequence number for the event.
+     *
+     * @var int
+     */
+    public $sequence;
+
+    /**
+     * The senders' email address.
+     *
+     * Note that this does not imply that this has to be used in a From: field
+     * if the message is sent by email. It may also be populated in Reply-To:
+     * or not at all.
+     *
+     * @var string
+     */
+    public $sender;
+
+    /**
+     * The name of the sender. This is often populated from a CN parameter from
+     * either the ORGANIZER or ATTENDEE, depending on the message.
+     *
+     * @var string|null
+     */
+    public $senderName;
+
+    /**
+     * The recipient's email address.
+     *
+     * @var string
+     */
+    public $recipient;
+
+    /**
+     * The name of the recipient. This is usually populated with the CN
+     * parameter from the ATTENDEE or ORGANIZER property, if it's available.
+     *
+     * @var string|null
+     */
+    public $recipientName;
+
+    /**
+     * After the message has been delivered, this should contain a string such
+     * as : 1.1;Sent or 1.2;Delivered.
+     *
+     * In case of a failure, this will hold the error status code.
+     *
+     * See:
+     * http://tools.ietf.org/html/rfc6638#section-7.3
+     *
+     * @var string
+     */
+    public $scheduleStatus;
+
+    /**
+     * The iCalendar / iTip body.
+     *
+     * @var \Sabre\VObject\Component\VCalendar
+     */
+    public $message;
+
+    /**
+     * This will be set to true, if the iTip broker considers the change
+     * 'significant'.
+     *
+     * In practice, this means that we'll only mark it true, if for instance
+     * DTSTART changed. This allows systems to only send iTip messages when
+     * significant changes happened. This is especially useful for iMip, as
+     * normally a ton of messages may be generated for normal calendar use.
+     *
+     * To see the list of properties that are considered 'significant', check
+     * out Sabre\VObject\ITip\Broker::$significantChangeProperties.
+     *
+     * @var bool
+     */
+    public $significantChange = true;
+
+    /**
+     * Returns the schedule status as a string.
+     *
+     * For example:
+     * 1.2
+     *
+     * @return mixed bool|string
+     */
+    function getScheduleStatus() {
+
+        if (!$this->scheduleStatus) {
+
+            return false;
+
+        } else {
+
+            list($scheduleStatus) = explode(';', $this->scheduleStatus);
+            return $scheduleStatus;
+
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/ITip/SameOrganizerForAllComponentsException.php b/vendor/sabre/vobject/lib/ITip/SameOrganizerForAllComponentsException.php
new file mode 100644
index 000000000..423b39831
--- /dev/null
+++ b/vendor/sabre/vobject/lib/ITip/SameOrganizerForAllComponentsException.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Sabre\VObject\ITip;
+
+/**
+ * SameOrganizerForAllComponentsException.
+ *
+ * This exception is emitted when an event is encountered with more than one
+ * component (e.g.: exceptions), but the organizer is not identical in every
+ * component.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class SameOrganizerForAllComponentsException extends ITipException {
+
+}
diff --git a/vendor/sabre/vobject/lib/InvalidDataException.php b/vendor/sabre/vobject/lib/InvalidDataException.php
new file mode 100644
index 000000000..50ebc0f49
--- /dev/null
+++ b/vendor/sabre/vobject/lib/InvalidDataException.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * This exception is thrown whenever an invalid value is found anywhere in a
+ * iCalendar or vCard object.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class InvalidDataException extends \Exception {
+}
diff --git a/vendor/sabre/vobject/lib/Node.php b/vendor/sabre/vobject/lib/Node.php
new file mode 100644
index 000000000..e2845da75
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Node.php
@@ -0,0 +1,265 @@
+<?php
+
+namespace Sabre\VObject;
+
+use Sabre\Xml;
+
+/**
+ * A node is the root class for every element in an iCalendar of vCard object.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+abstract class Node
+    implements \IteratorAggregate,
+               \ArrayAccess,
+               \Countable,
+               \JsonSerializable,
+               Xml\XmlSerializable {
+
+    /**
+     * The following constants are used by the validate() method.
+     *
+     * If REPAIR is set, the validator will attempt to repair any broken data
+     * (if possible).
+     */
+    const REPAIR = 1;
+
+    /**
+     * If this option is set, the validator will operate on the vcards on the
+     * assumption that the vcards need to be valid for CardDAV.
+     *
+     * This means for example that the UID is required, whereas it is not for
+     * regular vcards.
+     */
+    const PROFILE_CARDDAV = 2;
+
+    /**
+     * If this option is set, the validator will operate on iCalendar objects
+     * on the assumption that the vcards need to be valid for CalDAV.
+     *
+     * This means for example that calendars can only contain objects with
+     * identical component types and UIDs.
+     */
+    const PROFILE_CALDAV = 4;
+
+    /**
+     * Reference to the parent object, if this is not the top object.
+     *
+     * @var Node
+     */
+    public $parent;
+
+    /**
+     * Iterator override.
+     *
+     * @var ElementList
+     */
+    protected $iterator = null;
+
+    /**
+     * The root document.
+     *
+     * @var Component
+     */
+    protected $root;
+
+    /**
+     * Serializes the node into a mimedir format.
+     *
+     * @return string
+     */
+    abstract function serialize();
+
+    /**
+     * This method returns an array, with the representation as it should be
+     * encoded in JSON. This is used to create jCard or jCal documents.
+     *
+     * @return array
+     */
+    abstract function jsonSerialize();
+
+    /**
+     * This method serializes the data into XML. This is used to create xCard or
+     * xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    abstract function xmlSerialize(Xml\Writer $writer);
+
+    /**
+     * Call this method on a document if you're done using it.
+     *
+     * It's intended to remove all circular references, so PHP can easily clean
+     * it up.
+     *
+     * @return void
+     */
+    function destroy() {
+
+        $this->parent = null;
+        $this->root = null;
+
+    }
+
+    /* {{{ IteratorAggregator interface */
+
+    /**
+     * Returns the iterator for this object.
+     *
+     * @return ElementList
+     */
+    function getIterator() {
+
+        if (!is_null($this->iterator)) {
+            return $this->iterator;
+        }
+
+        return new ElementList([$this]);
+
+    }
+
+    /**
+     * Sets the overridden iterator.
+     *
+     * Note that this is not actually part of the iterator interface
+     *
+     * @param ElementList $iterator
+     *
+     * @return void
+     */
+    function setIterator(ElementList $iterator) {
+
+        $this->iterator = $iterator;
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on)
+     *   2 - An inconsequential issue
+     *   3 - A severe issue.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        return [];
+
+    }
+
+    /* }}} */
+
+    /* {{{ Countable interface */
+
+    /**
+     * Returns the number of elements.
+     *
+     * @return int
+     */
+    function count() {
+
+        $it = $this->getIterator();
+        return $it->count();
+
+    }
+
+    /* }}} */
+
+    /* {{{ ArrayAccess Interface */
+
+
+    /**
+     * Checks if an item exists through ArrayAccess.
+     *
+     * This method just forwards the request to the inner iterator
+     *
+     * @param int $offset
+     *
+     * @return bool
+     */
+    function offsetExists($offset) {
+
+        $iterator = $this->getIterator();
+        return $iterator->offsetExists($offset);
+
+    }
+
+    /**
+     * Gets an item through ArrayAccess.
+     *
+     * This method just forwards the request to the inner iterator
+     *
+     * @param int $offset
+     *
+     * @return mixed
+     */
+    function offsetGet($offset) {
+
+        $iterator = $this->getIterator();
+        return $iterator->offsetGet($offset);
+
+    }
+
+    /**
+     * Sets an item through ArrayAccess.
+     *
+     * This method just forwards the request to the inner iterator
+     *
+     * @param int $offset
+     * @param mixed $value
+     *
+     * @return void
+     */
+    function offsetSet($offset, $value) {
+
+        $iterator = $this->getIterator();
+        $iterator->offsetSet($offset, $value);
+
+    // @codeCoverageIgnoreStart
+    //
+    // This method always throws an exception, so we ignore the closing
+    // brace
+    }
+    // @codeCoverageIgnoreEnd
+
+    /**
+     * Sets an item through ArrayAccess.
+     *
+     * This method just forwards the request to the inner iterator
+     *
+     * @param int $offset
+     *
+     * @return void
+     */
+    function offsetUnset($offset) {
+
+        $iterator = $this->getIterator();
+        $iterator->offsetUnset($offset);
+
+    // @codeCoverageIgnoreStart
+    //
+    // This method always throws an exception, so we ignore the closing
+    // brace
+    }
+    // @codeCoverageIgnoreEnd
+
+    /* }}} */
+}
diff --git a/vendor/sabre/vobject/lib/PHPUnitAssertions.php b/vendor/sabre/vobject/lib/PHPUnitAssertions.php
new file mode 100644
index 000000000..87ec75e8f
--- /dev/null
+++ b/vendor/sabre/vobject/lib/PHPUnitAssertions.php
@@ -0,0 +1,82 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * PHPUnit Assertions
+ *
+ * This trait can be added to your unittest to make it easier to test iCalendar
+ * and/or vCards.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+trait PHPUnitAssertions {
+
+    /**
+     * This method tests wether two vcards or icalendar objects are
+     * semantically identical.
+     *
+     * It supports objects being supplied as strings, streams or
+     * Sabre\VObject\Component instances.
+     *
+     * PRODID is removed from both objects as this is often changes and would
+     * just get in the way.
+     *
+     * CALSCALE will automatically get removed if it's set to GREGORIAN.
+     *
+     * Any property that has the value **ANY** will be treated as a wildcard.
+     *
+     * @param resource|string|Component $expected
+     * @param resource|string|Component $actual
+     * @param string $message
+     */
+    function assertVObjectEqualsVObject($expected, $actual, $message = '') {
+
+        $self = $this;
+        $getObj = function($input) use ($self) {
+
+            if (is_resource($input)) {
+                $input = stream_get_contents($input);
+            }
+            if (is_string($input)) {
+                $input = Reader::read($input);
+            }
+            if (!$input instanceof Component) {
+                $this->fail('Input must be a string, stream or VObject component');
+            }
+            unset($input->PRODID);
+            if ($input instanceof Component\VCalendar && (string)$input->CALSCALE === 'GREGORIAN') {
+                unset($input->CALSCALE);
+            }
+            return $input;
+
+        };
+
+        $expected = $getObj($expected)->serialize();
+        $actual = $getObj($actual)->serialize();
+
+        // Finding wildcards in expected.
+        preg_match_all('|^([A-Z]+):\\*\\*ANY\\*\\*\r$|m', $expected, $matches, PREG_SET_ORDER);
+
+        foreach ($matches as $match) {
+
+            $actual = preg_replace(
+                '|^' . preg_quote($match[1], '|') . ':(.*)\r$|m',
+                $match[1] . ':**ANY**' . "\r",
+                $actual
+            );
+
+        }
+
+        $this->assertEquals(
+            $expected,
+            $actual,
+            $message
+        );
+
+    }
+
+
+}
diff --git a/vendor/sabre/vobject/lib/Parameter.php b/vendor/sabre/vobject/lib/Parameter.php
new file mode 100644
index 000000000..270643eab
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Parameter.php
@@ -0,0 +1,394 @@
+<?php
+
+namespace Sabre\VObject;
+
+use Sabre\Xml;
+use ArrayIterator;
+
+/**
+ * VObject Parameter.
+ *
+ * This class represents a parameter. A parameter is always tied to a property.
+ * In the case of:
+ *   DTSTART;VALUE=DATE:20101108
+ * VALUE=DATE would be the parameter name and value.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Parameter extends Node {
+
+    /**
+     * Parameter name.
+     *
+     * @var string
+     */
+    public $name;
+
+    /**
+     * vCard 2.1 allows parameters to be encoded without a name.
+     *
+     * We can deduce the parameter name based on it's value.
+     *
+     * @var bool
+     */
+    public $noName = false;
+
+    /**
+     * Parameter value.
+     *
+     * @var string
+     */
+    protected $value;
+
+    /**
+     * Sets up the object.
+     *
+     * It's recommended to use the create:: factory method instead.
+     *
+     * @param string $name
+     * @param string $value
+     */
+    function __construct(Document $root, $name, $value = null) {
+
+        $this->name = strtoupper($name);
+        $this->root = $root;
+        if (is_null($name)) {
+            $this->noName = true;
+            $this->name = static::guessParameterNameByValue($value);
+        }
+
+        // If guessParameterNameByValue() returns an empty string
+        // above, we're actually dealing with a parameter that has no value.
+        // In that case we have to move the value to the name.
+        if ($this->name === '') {
+            $this->noName = false;
+            $this->name = strtoupper($value);
+        } else {
+            $this->setValue($value);
+        }
+
+    }
+
+    /**
+     * Try to guess property name by value, can be used for vCard 2.1 nameless parameters.
+     *
+     * Figuring out what the name should have been. Note that a ton of
+     * these are rather silly in 2014 and would probably rarely be
+     * used, but we like to be complete.
+     *
+     * @param string $value
+     *
+     * @return string
+     */
+    static function guessParameterNameByValue($value) {
+        switch (strtoupper($value)) {
+
+            // Encodings
+            case '7-BIT' :
+            case 'QUOTED-PRINTABLE' :
+            case 'BASE64' :
+                $name = 'ENCODING';
+                break;
+
+            // Common types
+            case 'WORK' :
+            case 'HOME' :
+            case 'PREF' :
+
+            // Delivery Label Type
+            case 'DOM' :
+            case 'INTL' :
+            case 'POSTAL' :
+            case 'PARCEL' :
+
+            // Telephone types
+            case 'VOICE' :
+            case 'FAX' :
+            case 'MSG' :
+            case 'CELL' :
+            case 'PAGER' :
+            case 'BBS' :
+            case 'MODEM' :
+            case 'CAR' :
+            case 'ISDN' :
+            case 'VIDEO' :
+
+            // EMAIL types (lol)
+            case 'AOL' :
+            case 'APPLELINK' :
+            case 'ATTMAIL' :
+            case 'CIS' :
+            case 'EWORLD' :
+            case 'INTERNET' :
+            case 'IBMMAIL' :
+            case 'MCIMAIL' :
+            case 'POWERSHARE' :
+            case 'PRODIGY' :
+            case 'TLX' :
+            case 'X400' :
+
+            // Photo / Logo format types
+            case 'GIF' :
+            case 'CGM' :
+            case 'WMF' :
+            case 'BMP' :
+            case 'DIB' :
+            case 'PICT' :
+            case 'TIFF' :
+            case 'PDF' :
+            case 'PS' :
+            case 'JPEG' :
+            case 'MPEG' :
+            case 'MPEG2' :
+            case 'AVI' :
+            case 'QTIME' :
+
+            // Sound Digital Audio Type
+            case 'WAVE' :
+            case 'PCM' :
+            case 'AIFF' :
+
+            // Key types
+            case 'X509' :
+            case 'PGP' :
+                $name = 'TYPE';
+                break;
+
+            // Value types
+            case 'INLINE' :
+            case 'URL' :
+            case 'CONTENT-ID' :
+            case 'CID' :
+                $name = 'VALUE';
+                break;
+
+            default:
+                $name = '';
+        }
+
+        return $name;
+    }
+
+    /**
+     * Updates the current value.
+     *
+     * This may be either a single, or multiple strings in an array.
+     *
+     * @param string|array $value
+     *
+     * @return void
+     */
+    function setValue($value) {
+
+        $this->value = $value;
+
+    }
+
+    /**
+     * Returns the current value.
+     *
+     * This method will always return a string, or null. If there were multiple
+     * values, it will automatically concatenate them (separated by comma).
+     *
+     * @return string|null
+     */
+    function getValue() {
+
+        if (is_array($this->value)) {
+            return implode(',', $this->value);
+        } else {
+            return $this->value;
+        }
+
+    }
+
+    /**
+     * Sets multiple values for this parameter.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setParts(array $value) {
+
+        $this->value = $value;
+
+    }
+
+    /**
+     * Returns all values for this parameter.
+     *
+     * If there were no values, an empty array will be returned.
+     *
+     * @return array
+     */
+    function getParts() {
+
+        if (is_array($this->value)) {
+            return $this->value;
+        } elseif (is_null($this->value)) {
+            return [];
+        } else {
+            return [$this->value];
+        }
+
+    }
+
+    /**
+     * Adds a value to this parameter.
+     *
+     * If the argument is specified as an array, all items will be added to the
+     * parameter value list.
+     *
+     * @param string|array $part
+     *
+     * @return void
+     */
+    function addValue($part) {
+
+        if (is_null($this->value)) {
+            $this->value = $part;
+        } else {
+            $this->value = array_merge((array)$this->value, (array)$part);
+        }
+
+    }
+
+    /**
+     * Checks if this parameter contains the specified value.
+     *
+     * This is a case-insensitive match. It makes sense to call this for for
+     * instance the TYPE parameter, to see if it contains a keyword such as
+     * 'WORK' or 'FAX'.
+     *
+     * @param string $value
+     *
+     * @return bool
+     */
+    function has($value) {
+
+        return in_array(
+            strtolower($value),
+            array_map('strtolower', (array)$this->value)
+        );
+
+    }
+
+    /**
+     * Turns the object back into a serialized blob.
+     *
+     * @return string
+     */
+    function serialize() {
+
+        $value = $this->getParts();
+
+        if (count($value) === 0) {
+            return $this->name . '=';
+        }
+
+        if ($this->root->getDocumentType() === Document::VCARD21 && $this->noName) {
+
+            return implode(';', $value);
+
+        }
+
+        return $this->name . '=' . array_reduce(
+            $value,
+            function($out, $item) {
+
+                if (!is_null($out)) $out .= ',';
+
+                // If there's no special characters in the string, we'll use the simple
+                // format.
+                //
+                // The list of special characters is defined as:
+                //
+                // Any character except CONTROL, DQUOTE, ";", ":", ","
+                //
+                // by the iCalendar spec:
+                // https://tools.ietf.org/html/rfc5545#section-3.1
+                //
+                // And we add ^ to that because of:
+                // https://tools.ietf.org/html/rfc6868
+                //
+                // But we've found that iCal (7.0, shipped with OSX 10.9)
+                // severaly trips on + characters not being quoted, so we
+                // added + as well.
+                if (!preg_match('#(?: [\n":;\^,\+] )#x', $item)) {
+                    return $out . $item;
+                } else {
+                    // Enclosing in double-quotes, and using RFC6868 for encoding any
+                    // special characters
+                    $out .= '"' . strtr(
+                        $item,
+                        [
+                            '^'  => '^^',
+                            "\n" => '^n',
+                            '"'  => '^\'',
+                        ]
+                    ) . '"';
+                    return $out;
+                }
+
+            }
+        );
+
+    }
+
+    /**
+     * This method returns an array, with the representation as it should be
+     * encoded in JSON. This is used to create jCard or jCal documents.
+     *
+     * @return array
+     */
+    function jsonSerialize() {
+
+        return $this->value;
+
+    }
+
+    /**
+     * This method serializes the data into XML. This is used to create xCard or
+     * xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    function xmlSerialize(Xml\Writer $writer) {
+
+        foreach (explode(',', $this->value) as $value) {
+            $writer->writeElement('text', $value);
+        }
+
+    }
+
+    /**
+     * Called when this object is being cast to a string.
+     *
+     * @return string
+     */
+    function __toString() {
+
+        return (string)$this->getValue();
+
+    }
+
+    /**
+     * Returns the iterator for this object.
+     *
+     * @return ElementList
+     */
+    function getIterator() {
+
+        if (!is_null($this->iterator))
+            return $this->iterator;
+
+        return $this->iterator = new ArrayIterator((array)$this->value);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/ParseException.php b/vendor/sabre/vobject/lib/ParseException.php
new file mode 100644
index 000000000..d96d20720
--- /dev/null
+++ b/vendor/sabre/vobject/lib/ParseException.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * Exception thrown by Reader if an invalid object was attempted to be parsed.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ParseException extends \Exception {
+}
diff --git a/vendor/sabre/vobject/lib/Parser/Json.php b/vendor/sabre/vobject/lib/Parser/Json.php
new file mode 100644
index 000000000..370c981a8
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Parser/Json.php
@@ -0,0 +1,197 @@
+<?php
+
+namespace Sabre\VObject\Parser;
+
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VCard;
+use Sabre\VObject\ParseException;
+use Sabre\VObject\EofException;
+
+/**
+ * Json Parser.
+ *
+ * This parser parses both the jCal and jCard formats.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Json extends Parser {
+
+    /**
+     * The input data.
+     *
+     * @var array
+     */
+    protected $input;
+
+    /**
+     * Root component.
+     *
+     * @var Document
+     */
+    protected $root;
+
+    /**
+     * This method starts the parsing process.
+     *
+     * If the input was not supplied during construction, it's possible to pass
+     * it here instead.
+     *
+     * If either input or options are not supplied, the defaults will be used.
+     *
+     * @param resource|string|array|null $input
+     * @param int $options
+     *
+     * @return Sabre\VObject\Document
+     */
+    function parse($input = null, $options = 0) {
+
+        if (!is_null($input)) {
+            $this->setInput($input);
+        }
+        if (is_null($this->input)) {
+            throw new EofException('End of input stream, or no input supplied');
+        }
+
+        if (0 !== $options) {
+            $this->options = $options;
+        }
+
+        switch ($this->input[0]) {
+            case 'vcalendar' :
+                $this->root = new VCalendar([], false);
+                break;
+            case 'vcard' :
+                $this->root = new VCard([], false);
+                break;
+            default :
+                throw new ParseException('The root component must either be a vcalendar, or a vcard');
+
+        }
+        foreach ($this->input[1] as $prop) {
+            $this->root->add($this->parseProperty($prop));
+        }
+        if (isset($this->input[2])) foreach ($this->input[2] as $comp) {
+            $this->root->add($this->parseComponent($comp));
+        }
+
+        // Resetting the input so we can throw an feof exception the next time.
+        $this->input = null;
+
+        return $this->root;
+
+    }
+
+    /**
+     * Parses a component.
+     *
+     * @param array $jComp
+     *
+     * @return \Sabre\VObject\Component
+     */
+    function parseComponent(array $jComp) {
+
+        // We can remove $self from PHP 5.4 onward.
+        $self = $this;
+
+        $properties = array_map(
+            function($jProp) use ($self) {
+                return $self->parseProperty($jProp);
+            },
+            $jComp[1]
+        );
+
+        if (isset($jComp[2])) {
+
+            $components = array_map(
+                function($jComp) use ($self) {
+                    return $self->parseComponent($jComp);
+                },
+                $jComp[2]
+            );
+
+        } else $components = [];
+
+        return $this->root->createComponent(
+            $jComp[0],
+            array_merge($properties, $components),
+            $defaults = false
+        );
+
+    }
+
+    /**
+     * Parses properties.
+     *
+     * @param array $jProp
+     *
+     * @return \Sabre\VObject\Property
+     */
+    function parseProperty(array $jProp) {
+
+        list(
+            $propertyName,
+            $parameters,
+            $valueType
+        ) = $jProp;
+
+        $propertyName = strtoupper($propertyName);
+
+        // This is the default class we would be using if we didn't know the
+        // value type. We're using this value later in this function.
+        $defaultPropertyClass = $this->root->getClassNameForPropertyName($propertyName);
+
+        $parameters = (array)$parameters;
+
+        $value = array_slice($jProp, 3);
+
+        $valueType = strtoupper($valueType);
+
+        if (isset($parameters['group'])) {
+            $propertyName = $parameters['group'] . '.' . $propertyName;
+            unset($parameters['group']);
+        }
+
+        $prop = $this->root->createProperty($propertyName, null, $parameters, $valueType);
+        $prop->setJsonValue($value);
+
+        // We have to do something awkward here. FlatText as well as Text
+        // represents TEXT values. We have to normalize these here. In the
+        // future we can get rid of FlatText once we're allowed to break BC
+        // again.
+        if ($defaultPropertyClass === 'Sabre\VObject\Property\FlatText') {
+            $defaultPropertyClass = 'Sabre\VObject\Property\Text';
+        }
+
+        // If the value type we received (e.g.: TEXT) was not the default value
+        // type for the given property (e.g.: BDAY), we need to add a VALUE=
+        // parameter.
+        if ($defaultPropertyClass !== get_class($prop)) {
+            $prop["VALUE"] = $valueType;
+        }
+
+        return $prop;
+
+    }
+
+    /**
+     * Sets the input data.
+     *
+     * @param resource|string|array $input
+     *
+     * @return void
+     */
+    function setInput($input) {
+
+        if (is_resource($input)) {
+            $input = stream_get_contents($input);
+        }
+        if (is_string($input)) {
+            $input = json_decode($input);
+        }
+        $this->input = $input;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Parser/MimeDir.php b/vendor/sabre/vobject/lib/Parser/MimeDir.php
new file mode 100644
index 000000000..6a7f9317b
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Parser/MimeDir.php
@@ -0,0 +1,696 @@
+<?php
+
+namespace Sabre\VObject\Parser;
+
+use Sabre\VObject\ParseException;
+use Sabre\VObject\EofException;
+use Sabre\VObject\Component;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VCard;
+use Sabre\VObject\Document;
+
+/**
+ * MimeDir parser.
+ *
+ * This class parses iCalendar 2.0 and vCard 2.1, 3.0 and 4.0 files. This
+ * parser will return one of the following two objects from the parse method:
+ *
+ * Sabre\VObject\Component\VCalendar
+ * Sabre\VObject\Component\VCard
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class MimeDir extends Parser {
+
+    /**
+     * The input stream.
+     *
+     * @var resource
+     */
+    protected $input;
+
+    /**
+     * Root component.
+     *
+     * @var Component
+     */
+    protected $root;
+
+    /**
+     * By default all input will be assumed to be UTF-8.
+     *
+     * However, both iCalendar and vCard might be encoded using different
+     * character sets. The character set is usually set in the mime-type.
+     *
+     * If this is the case, use setEncoding to specify that a different
+     * encoding will be used. If this is set, the parser will automatically
+     * convert all incoming data to UTF-8.
+     *
+     * @var string
+     */
+    protected $charset = 'UTF-8';
+
+    /**
+     * The list of character sets we support when decoding.
+     *
+     * This would be a const expression but for now we need to support PHP 5.5
+     */
+    protected static $SUPPORTED_CHARSETS = [
+        'UTF-8',
+        'ISO-8859-1',
+        'Windows-1252',
+    ];
+
+    /**
+     * Parses an iCalendar or vCard file.
+     *
+     * Pass a stream or a string. If null is parsed, the existing buffer is
+     * used.
+     *
+     * @param string|resource|null $input
+     * @param int $options
+     *
+     * @return Sabre\VObject\Document
+     */
+    function parse($input = null, $options = 0) {
+
+        $this->root = null;
+
+        if (!is_null($input)) {
+            $this->setInput($input);
+        }
+
+        if (0 !== $options) {
+            $this->options = $options;
+        }
+
+        $this->parseDocument();
+
+        return $this->root;
+
+    }
+
+    /**
+     * By default all input will be assumed to be UTF-8.
+     *
+     * However, both iCalendar and vCard might be encoded using different
+     * character sets. The character set is usually set in the mime-type.
+     *
+     * If this is the case, use setEncoding to specify that a different
+     * encoding will be used. If this is set, the parser will automatically
+     * convert all incoming data to UTF-8.
+     *
+     * @param string $charset
+     */
+    function setCharset($charset) {
+
+        if (!in_array($charset, self::$SUPPORTED_CHARSETS)) {
+            throw new \InvalidArgumentException('Unsupported encoding. (Supported encodings: ' . implode(', ', self::$SUPPORTED_CHARSETS) . ')');
+        }
+        $this->charset = $charset;
+
+    }
+
+    /**
+     * Sets the input buffer. Must be a string or stream.
+     *
+     * @param resource|string $input
+     *
+     * @return void
+     */
+    function setInput($input) {
+
+        // Resetting the parser
+        $this->lineIndex = 0;
+        $this->startLine = 0;
+
+        if (is_string($input)) {
+            // Convering to a stream.
+            $stream = fopen('php://temp', 'r+');
+            fwrite($stream, $input);
+            rewind($stream);
+            $this->input = $stream;
+        } elseif (is_resource($input)) {
+            $this->input = $input;
+        } else {
+            throw new \InvalidArgumentException('This parser can only read from strings or streams.');
+        }
+
+    }
+
+    /**
+     * Parses an entire document.
+     *
+     * @return void
+     */
+    protected function parseDocument() {
+
+        $line = $this->readLine();
+
+        // BOM is ZERO WIDTH NO-BREAK SPACE (U+FEFF).
+        // It's 0xEF 0xBB 0xBF in UTF-8 hex.
+        if (3 <= strlen($line)
+            && ord($line[0]) === 0xef
+            && ord($line[1]) === 0xbb
+            && ord($line[2]) === 0xbf) {
+            $line = substr($line, 3);
+        }
+
+        switch (strtoupper($line)) {
+            case 'BEGIN:VCALENDAR' :
+                $class = VCalendar::$componentMap['VCALENDAR'];
+                break;
+            case 'BEGIN:VCARD' :
+                $class = VCard::$componentMap['VCARD'];
+                break;
+            default :
+                throw new ParseException('This parser only supports VCARD and VCALENDAR files');
+        }
+
+        $this->root = new $class([], false);
+
+        while (true) {
+
+            // Reading until we hit END:
+            $line = $this->readLine();
+            if (strtoupper(substr($line, 0, 4)) === 'END:') {
+                break;
+            }
+            $result = $this->parseLine($line);
+            if ($result) {
+                $this->root->add($result);
+            }
+
+        }
+
+        $name = strtoupper(substr($line, 4));
+        if ($name !== $this->root->name) {
+            throw new ParseException('Invalid MimeDir file. expected: "END:' . $this->root->name . '" got: "END:' . $name . '"');
+        }
+
+    }
+
+    /**
+     * Parses a line, and if it hits a component, it will also attempt to parse
+     * the entire component.
+     *
+     * @param string $line Unfolded line
+     *
+     * @return Node
+     */
+    protected function parseLine($line) {
+
+        // Start of a new component
+        if (strtoupper(substr($line, 0, 6)) === 'BEGIN:') {
+
+            $component = $this->root->createComponent(substr($line, 6), [], false);
+
+            while (true) {
+
+                // Reading until we hit END:
+                $line = $this->readLine();
+                if (strtoupper(substr($line, 0, 4)) === 'END:') {
+                    break;
+                }
+                $result = $this->parseLine($line);
+                if ($result) {
+                    $component->add($result);
+                }
+
+            }
+
+            $name = strtoupper(substr($line, 4));
+            if ($name !== $component->name) {
+                throw new ParseException('Invalid MimeDir file. expected: "END:' . $component->name . '" got: "END:' . $name . '"');
+            }
+
+            return $component;
+
+        } else {
+
+            // Property reader
+            $property = $this->readProperty($line);
+            if (!$property) {
+                // Ignored line
+                return false;
+            }
+            return $property;
+
+        }
+
+    }
+
+    /**
+     * We need to look ahead 1 line every time to see if we need to 'unfold'
+     * the next line.
+     *
+     * If that was not the case, we store it here.
+     *
+     * @var null|string
+     */
+    protected $lineBuffer;
+
+    /**
+     * The real current line number.
+     */
+    protected $lineIndex = 0;
+
+    /**
+     * In the case of unfolded lines, this property holds the line number for
+     * the start of the line.
+     *
+     * @var int
+     */
+    protected $startLine = 0;
+
+    /**
+     * Contains a 'raw' representation of the current line.
+     *
+     * @var string
+     */
+    protected $rawLine;
+
+    /**
+     * Reads a single line from the buffer.
+     *
+     * This method strips any newlines and also takes care of unfolding.
+     *
+     * @throws \Sabre\VObject\EofException
+     *
+     * @return string
+     */
+    protected function readLine() {
+
+        if (!is_null($this->lineBuffer)) {
+            $rawLine = $this->lineBuffer;
+            $this->lineBuffer = null;
+        } else {
+            do {
+                $eof = feof($this->input);
+
+                $rawLine = fgets($this->input);
+
+                if ($eof || (feof($this->input) && $rawLine === false)) {
+                    throw new EofException('End of document reached prematurely');
+                }
+                if ($rawLine === false) {
+                    throw new ParseException('Error reading from input stream');
+                }
+                $rawLine = rtrim($rawLine, "\r\n");
+            } while ($rawLine === ''); // Skipping empty lines
+            $this->lineIndex++;
+        }
+        $line = $rawLine;
+
+        $this->startLine = $this->lineIndex;
+
+        // Looking ahead for folded lines.
+        while (true) {
+
+            $nextLine = rtrim(fgets($this->input), "\r\n");
+            $this->lineIndex++;
+            if (!$nextLine) {
+                break;
+            }
+            if ($nextLine[0] === "\t" || $nextLine[0] === " ") {
+                $line .= substr($nextLine, 1);
+                $rawLine .= "\n " . substr($nextLine, 1);
+            } else {
+                $this->lineBuffer = $nextLine;
+                break;
+            }
+
+        }
+        $this->rawLine = $rawLine;
+        return $line;
+
+    }
+
+    /**
+     * Reads a property or component from a line.
+     *
+     * @return void
+     */
+    protected function readProperty($line) {
+
+        if ($this->options & self::OPTION_FORGIVING) {
+            $propNameToken = 'A-Z0-9\-\._\\/';
+        } else {
+            $propNameToken = 'A-Z0-9\-\.';
+        }
+
+        $paramNameToken = 'A-Z0-9\-';
+        $safeChar = '^";:,';
+        $qSafeChar = '^"';
+
+        $regex = "/
+            ^(?P<name> [$propNameToken]+ ) (?=[;:])        # property name
+            |
+            (?<=:)(?P<propValue> .+)$                      # property value
+            |
+            ;(?P<paramName> [$paramNameToken]+) (?=[=;:])  # parameter name
+            |
+            (=|,)(?P<paramValue>                           # parameter value
+                (?: [$safeChar]*) |
+                \"(?: [$qSafeChar]+)\"
+            ) (?=[;:,])
+            /xi";
+
+        //echo $regex, "\n"; die();
+        preg_match_all($regex, $line, $matches,  PREG_SET_ORDER);
+
+        $property = [
+            'name'       => null,
+            'parameters' => [],
+            'value'      => null
+        ];
+
+        $lastParam = null;
+
+        /**
+         * Looping through all the tokens.
+         *
+         * Note that we are looping through them in reverse order, because if a
+         * sub-pattern matched, the subsequent named patterns will not show up
+         * in the result.
+         */
+        foreach ($matches as $match) {
+
+            if (isset($match['paramValue'])) {
+                if ($match['paramValue'] && $match['paramValue'][0] === '"') {
+                    $value = substr($match['paramValue'], 1, -1);
+                } else {
+                    $value = $match['paramValue'];
+                }
+
+                $value = $this->unescapeParam($value);
+
+                if (is_null($lastParam)) {
+                    throw new ParseException('Invalid Mimedir file. Line starting at ' . $this->startLine . ' did not follow iCalendar/vCard conventions');
+                }
+                if (is_null($property['parameters'][$lastParam])) {
+                    $property['parameters'][$lastParam] = $value;
+                } elseif (is_array($property['parameters'][$lastParam])) {
+                    $property['parameters'][$lastParam][] = $value;
+                } else {
+                    $property['parameters'][$lastParam] = [
+                        $property['parameters'][$lastParam],
+                        $value
+                    ];
+                }
+                continue;
+            }
+            if (isset($match['paramName'])) {
+                $lastParam = strtoupper($match['paramName']);
+                if (!isset($property['parameters'][$lastParam])) {
+                    $property['parameters'][$lastParam] = null;
+                }
+                continue;
+            }
+            if (isset($match['propValue'])) {
+                $property['value'] = $match['propValue'];
+                continue;
+            }
+            if (isset($match['name']) && $match['name']) {
+                $property['name'] = strtoupper($match['name']);
+                continue;
+            }
+
+            // @codeCoverageIgnoreStart
+            throw new \LogicException('This code should not be reachable');
+            // @codeCoverageIgnoreEnd
+
+        }
+
+        if (is_null($property['value'])) {
+            $property['value'] = '';
+        }
+        if (!$property['name']) {
+            if ($this->options & self::OPTION_IGNORE_INVALID_LINES) {
+                return false;
+            }
+            throw new ParseException('Invalid Mimedir file. Line starting at ' . $this->startLine . ' did not follow iCalendar/vCard conventions');
+        }
+
+        // vCard 2.1 states that parameters may appear without a name, and only
+        // a value. We can deduce the value based on it's name.
+        //
+        // Our parser will get those as parameters without a value instead, so
+        // we're filtering these parameters out first.
+        $namedParameters = [];
+        $namelessParameters = [];
+
+        foreach ($property['parameters'] as $name => $value) {
+            if (!is_null($value)) {
+                $namedParameters[$name] = $value;
+            } else {
+                $namelessParameters[] = $name;
+            }
+        }
+
+        $propObj = $this->root->createProperty($property['name'], null, $namedParameters);
+
+        foreach ($namelessParameters as $namelessParameter) {
+            $propObj->add(null, $namelessParameter);
+        }
+
+        if (strtoupper($propObj['ENCODING']) === 'QUOTED-PRINTABLE') {
+            $propObj->setQuotedPrintableValue($this->extractQuotedPrintableValue());
+        } else {
+            $charset = $this->charset;
+            if ($this->root->getDocumentType() === Document::VCARD21 && isset($propObj['CHARSET'])) {
+                // vCard 2.1 allows the character set to be specified per property.
+                $charset = (string)$propObj['CHARSET'];
+            }
+            switch ($charset) {
+                case 'UTF-8' :
+                    break;
+                case 'ISO-8859-1' :
+                    $property['value'] = utf8_encode($property['value']);
+                    break;
+                case 'Windows-1252' :
+                    $property['value'] = mb_convert_encoding($property['value'], 'UTF-8', $charset);
+                    break;
+                default :
+                    throw new ParseException('Unsupported CHARSET: ' . $propObj['CHARSET']);
+            }
+            $propObj->setRawMimeDirValue($property['value']);
+        }
+
+        return $propObj;
+
+    }
+
+    /**
+     * Unescapes a property value.
+     *
+     * vCard 2.1 says:
+     *   * Semi-colons must be escaped in some property values, specifically
+     *     ADR, ORG and N.
+     *   * Semi-colons must be escaped in parameter values, because semi-colons
+     *     are also use to separate values.
+     *   * No mention of escaping backslashes with another backslash.
+     *   * newlines are not escaped either, instead QUOTED-PRINTABLE is used to
+     *     span values over more than 1 line.
+     *
+     * vCard 3.0 says:
+     *   * (rfc2425) Backslashes, newlines (\n or \N) and comma's must be
+     *     escaped, all time time.
+     *   * Comma's are used for delimeters in multiple values
+     *   * (rfc2426) Adds to to this that the semi-colon MUST also be escaped,
+     *     as in some properties semi-colon is used for separators.
+     *   * Properties using semi-colons: N, ADR, GEO, ORG
+     *   * Both ADR and N's individual parts may be broken up further with a
+     *     comma.
+     *   * Properties using commas: NICKNAME, CATEGORIES
+     *
+     * vCard 4.0 (rfc6350) says:
+     *   * Commas must be escaped.
+     *   * Semi-colons may be escaped, an unescaped semi-colon _may_ be a
+     *     delimiter, depending on the property.
+     *   * Backslashes must be escaped
+     *   * Newlines must be escaped as either \N or \n.
+     *   * Some compound properties may contain multiple parts themselves, so a
+     *     comma within a semi-colon delimited property may also be unescaped
+     *     to denote multiple parts _within_ the compound property.
+     *   * Text-properties using semi-colons: N, ADR, ORG, CLIENTPIDMAP.
+     *   * Text-properties using commas: NICKNAME, RELATED, CATEGORIES, PID.
+     *
+     * Even though the spec says that commas must always be escaped, the
+     * example for GEO in Section 6.5.2 seems to violate this.
+     *
+     * iCalendar 2.0 (rfc5545) says:
+     *   * Commas or semi-colons may be used as delimiters, depending on the
+     *     property.
+     *   * Commas, semi-colons, backslashes, newline (\N or \n) are always
+     *     escaped, unless they are delimiters.
+     *   * Colons shall not be escaped.
+     *   * Commas can be considered the 'default delimiter' and is described as
+     *     the delimiter in cases where the order of the multiple values is
+     *     insignificant.
+     *   * Semi-colons are described as the delimiter for 'structured values'.
+     *     They are specifically used in Semi-colons are used as a delimiter in
+     *     REQUEST-STATUS, RRULE, GEO and EXRULE. EXRULE is deprecated however.
+     *
+     * Now for the parameters
+     *
+     * If delimiter is not set (null) this method will just return a string.
+     * If it's a comma or a semi-colon the string will be split on those
+     * characters, and always return an array.
+     *
+     * @param string $input
+     * @param string $delimiter
+     *
+     * @return string|string[]
+     */
+    static function unescapeValue($input, $delimiter = ';') {
+
+        $regex = '#  (?: (\\\\ (?: \\\\ | N | n | ; | , ) )';
+        if ($delimiter) {
+            $regex .= ' | (' . $delimiter . ')';
+        }
+        $regex .= ') #x';
+
+        $matches = preg_split($regex, $input, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+
+        $resultArray = [];
+        $result = '';
+
+        foreach ($matches as $match) {
+
+            switch ($match) {
+                case '\\\\' :
+                    $result .= '\\';
+                    break;
+                case '\N' :
+                case '\n' :
+                    $result .= "\n";
+                    break;
+                case '\;' :
+                    $result .= ';';
+                    break;
+                case '\,' :
+                    $result .= ',';
+                    break;
+                case $delimiter :
+                    $resultArray[] = $result;
+                    $result = '';
+                    break;
+                default :
+                    $result .= $match;
+                    break;
+
+            }
+
+        }
+
+        $resultArray[] = $result;
+        return $delimiter ? $resultArray : $result;
+
+    }
+
+    /**
+     * Unescapes a parameter value.
+     *
+     * vCard 2.1:
+     *   * Does not mention a mechanism for this. In addition, double quotes
+     *     are never used to wrap values.
+     *   * This means that parameters can simply not contain colons or
+     *     semi-colons.
+     *
+     * vCard 3.0 (rfc2425, rfc2426):
+     *   * Parameters _may_ be surrounded by double quotes.
+     *   * If this is not the case, semi-colon, colon and comma may simply not
+     *     occur (the comma used for multiple parameter values though).
+     *   * If it is surrounded by double-quotes, it may simply not contain
+     *     double-quotes.
+     *   * This means that a parameter can in no case encode double-quotes, or
+     *     newlines.
+     *
+     * vCard 4.0 (rfc6350)
+     *   * Behavior seems to be identical to vCard 3.0
+     *
+     * iCalendar 2.0 (rfc5545)
+     *   * Behavior seems to be identical to vCard 3.0
+     *
+     * Parameter escaping mechanism (rfc6868) :
+     *   * This rfc describes a new way to escape parameter values.
+     *   * New-line is encoded as ^n
+     *   * ^ is encoded as ^^.
+     *   * " is encoded as ^'
+     *
+     * @param string $input
+     *
+     * @return void
+     */
+    private function unescapeParam($input) {
+
+        return
+            preg_replace_callback(
+                '#(\^(\^|n|\'))#',
+                function($matches) {
+                    switch ($matches[2]) {
+                        case 'n' :
+                            return "\n";
+                        case '^' :
+                            return '^';
+                        case '\'' :
+                            return '"';
+
+                    // @codeCoverageIgnoreStart
+                    }
+                    // @codeCoverageIgnoreEnd
+                },
+                $input
+            );
+    }
+
+    /**
+     * Gets the full quoted printable value.
+     *
+     * We need a special method for this, because newlines have both a meaning
+     * in vCards, and in QuotedPrintable.
+     *
+     * This method does not do any decoding.
+     *
+     * @return string
+     */
+    private function extractQuotedPrintableValue() {
+
+        // We need to parse the raw line again to get the start of the value.
+        //
+        // We are basically looking for the first colon (:), but we need to
+        // skip over the parameters first, as they may contain one.
+        $regex = '/^
+            (?: [^:])+ # Anything but a colon
+            (?: "[^"]")* # A parameter in double quotes
+            : # start of the value we really care about
+            (.*)$
+        /xs';
+
+        preg_match($regex, $this->rawLine, $matches);
+
+        $value = $matches[1];
+        // Removing the first whitespace character from every line. Kind of
+        // like unfolding, but we keep the newline.
+        $value = str_replace("\n ", "\n", $value);
+
+        // Microsoft products don't always correctly fold lines, they may be
+        // missing a whitespace. So if 'forgiving' is turned on, we will take
+        // those as well.
+        if ($this->options & self::OPTION_FORGIVING) {
+            while (substr($value, -1) === '=') {
+                // Reading the line
+                $this->readLine();
+                // Grabbing the raw form
+                $value .= "\n" . $this->rawLine;
+            }
+        }
+
+        return $value;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Parser/Parser.php b/vendor/sabre/vobject/lib/Parser/Parser.php
new file mode 100644
index 000000000..ca8bc0add
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Parser/Parser.php
@@ -0,0 +1,80 @@
+<?php
+
+namespace Sabre\VObject\Parser;
+
+/**
+ * Abstract parser.
+ *
+ * This class serves as a base-class for the different parsers.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+abstract class Parser {
+
+    /**
+     * Turning on this option makes the parser more forgiving.
+     *
+     * In the case of the MimeDir parser, this means that the parser will
+     * accept slashes and underscores in property names, and it will also
+     * attempt to fix Microsoft vCard 2.1's broken line folding.
+     */
+    const OPTION_FORGIVING = 1;
+
+    /**
+     * If this option is turned on, any lines we cannot parse will be ignored
+     * by the reader.
+     */
+    const OPTION_IGNORE_INVALID_LINES = 2;
+
+    /**
+     * Bitmask of parser options.
+     *
+     * @var int
+     */
+    protected $options;
+
+    /**
+     * Creates the parser.
+     *
+     * Optionally, it's possible to parse the input stream here.
+     *
+     * @param mixed $input
+     * @param int $options Any parser options (OPTION constants).
+     *
+     * @return void
+     */
+    function __construct($input = null, $options = 0) {
+
+        if (!is_null($input)) {
+            $this->setInput($input);
+        }
+        $this->options = $options;
+    }
+
+    /**
+     * This method starts the parsing process.
+     *
+     * If the input was not supplied during construction, it's possible to pass
+     * it here instead.
+     *
+     * If either input or options are not supplied, the defaults will be used.
+     *
+     * @param mixed $input
+     * @param int $options
+     *
+     * @return array
+     */
+    abstract function parse($input = null, $options = 0);
+
+    /**
+     * Sets the input data.
+     *
+     * @param mixed $input
+     *
+     * @return void
+     */
+    abstract function setInput($input);
+
+}
diff --git a/vendor/sabre/vobject/lib/Parser/XML.php b/vendor/sabre/vobject/lib/Parser/XML.php
new file mode 100644
index 000000000..060a7fe2e
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Parser/XML.php
@@ -0,0 +1,428 @@
+<?php
+
+namespace Sabre\VObject\Parser;
+
+use Sabre\VObject\Component;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VCard;
+use Sabre\VObject\EofException;
+use Sabre\VObject\ParseException;
+use Sabre\Xml as SabreXml;
+
+/**
+ * XML Parser.
+ *
+ * This parser parses both the xCal and xCard formats.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Ivan Enderlin
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class XML extends Parser {
+
+    const XCAL_NAMESPACE  = 'urn:ietf:params:xml:ns:icalendar-2.0';
+    const XCARD_NAMESPACE = 'urn:ietf:params:xml:ns:vcard-4.0';
+
+    /**
+     * The input data.
+     *
+     * @var array
+     */
+    protected $input;
+
+    /**
+     * A pointer/reference to the input.
+     *
+     * @var array
+     */
+    private $pointer;
+
+    /**
+     * Document, root component.
+     *
+     * @var Sabre\VObject\Document
+     */
+    protected $root;
+
+    /**
+     * Creates the parser.
+     *
+     * Optionally, it's possible to parse the input stream here.
+     *
+     * @param mixed $input
+     * @param int $options Any parser options (OPTION constants).
+     *
+     * @return void
+     */
+    function __construct($input = null, $options = 0) {
+
+        if (0 === $options) {
+            $options = parent::OPTION_FORGIVING;
+        }
+
+        parent::__construct($input, $options);
+
+    }
+
+    /**
+     * Parse xCal or xCard.
+     *
+     * @param resource|string $input
+     * @param int $options
+     *
+     * @throws \Exception
+     *
+     * @return Sabre\VObject\Document
+     */
+    function parse($input = null, $options = 0) {
+
+        if (!is_null($input)) {
+            $this->setInput($input);
+        }
+
+        if (0 !== $options) {
+            $this->options = $options;
+        }
+
+        if (is_null($this->input)) {
+            throw new EofException('End of input stream, or no input supplied');
+        }
+
+        switch ($this->input['name']) {
+
+            case '{' . self::XCAL_NAMESPACE . '}icalendar':
+                $this->root = new VCalendar([], false);
+                $this->pointer = &$this->input['value'][0];
+                $this->parseVCalendarComponents($this->root);
+                break;
+
+            case '{' . self::XCARD_NAMESPACE . '}vcards':
+                foreach ($this->input['value'] as &$vCard) {
+
+                    $this->root = new VCard(['version' => '4.0'], false);
+                    $this->pointer  = &$vCard;
+                    $this->parseVCardComponents($this->root);
+
+                    // We just parse the first <vcard /> element.
+                    break;
+
+                }
+                break;
+
+            default:
+                throw new ParseException('Unsupported XML standard');
+
+        }
+
+        return $this->root;
+    }
+
+    /**
+     * Parse a xCalendar component.
+     *
+     * @param Component $parentComponent
+     *
+     * @return void
+     */
+    protected function parseVCalendarComponents(Component $parentComponent) {
+
+        foreach ($this->pointer['value'] ?: [] as $children) {
+
+            switch (static::getTagName($children['name'])) {
+
+                case 'properties':
+                    $this->pointer = &$children['value'];
+                    $this->parseProperties($parentComponent);
+                    break;
+
+                case 'components':
+                    $this->pointer = &$children;
+                    $this->parseComponent($parentComponent);
+                    break;
+            }
+        }
+
+    }
+
+    /**
+     * Parse a xCard component.
+     *
+     * @param Component $parentComponent
+     *
+     * @return void
+     */
+    protected function parseVCardComponents(Component $parentComponent) {
+
+        $this->pointer = &$this->pointer['value'];
+        $this->parseProperties($parentComponent);
+
+    }
+
+    /**
+     * Parse xCalendar and xCard properties.
+     *
+     * @param Component $parentComponent
+     * @param string  $propertyNamePrefix
+     *
+     * @return void
+     */
+    protected function parseProperties(Component $parentComponent, $propertyNamePrefix = '') {
+
+        foreach ($this->pointer ?: [] as $xmlProperty) {
+
+            list($namespace, $tagName) = SabreXml\Service::parseClarkNotation($xmlProperty['name']);
+
+            $propertyName       = $tagName;
+            $propertyValue      = [];
+            $propertyParameters = [];
+            $propertyType       = 'text';
+
+            // A property which is not part of the standard.
+            if ($namespace !== self::XCAL_NAMESPACE
+                && $namespace !== self::XCARD_NAMESPACE) {
+
+                $propertyName = 'xml';
+                $value = '<' . $tagName . ' xmlns="' . $namespace . '"';
+
+                foreach ($xmlProperty['attributes'] as $attributeName => $attributeValue) {
+                    $value .= ' ' . $attributeName . '="' . str_replace('"', '\"', $attributeValue) . '"';
+                }
+
+                $value .= '>' . $xmlProperty['value'] . '</' . $tagName . '>';
+
+                $propertyValue = [$value];
+
+                $this->createProperty(
+                    $parentComponent,
+                    $propertyName,
+                    $propertyParameters,
+                    $propertyType,
+                    $propertyValue
+                );
+
+                continue;
+            }
+
+            // xCard group.
+            if ($propertyName === 'group') {
+
+                if (!isset($xmlProperty['attributes']['name'])) {
+                    continue;
+                }
+
+                $this->pointer = &$xmlProperty['value'];
+                $this->parseProperties(
+                    $parentComponent,
+                    strtoupper($xmlProperty['attributes']['name']) . '.'
+                );
+
+                continue;
+
+            }
+
+            // Collect parameters.
+            foreach ($xmlProperty['value'] as $i => $xmlPropertyChild) {
+
+                if (!is_array($xmlPropertyChild)
+                    || 'parameters' !== static::getTagName($xmlPropertyChild['name']))
+                    continue;
+
+                $xmlParameters = $xmlPropertyChild['value'];
+
+                foreach ($xmlParameters as $xmlParameter) {
+
+                    $propertyParameterValues = [];
+
+                    foreach ($xmlParameter['value'] as $xmlParameterValues) {
+                        $propertyParameterValues[] = $xmlParameterValues['value'];
+                    }
+
+                    $propertyParameters[static::getTagName($xmlParameter['name'])]
+                        = implode(',', $propertyParameterValues);
+
+                }
+
+                array_splice($xmlProperty['value'], $i, 1);
+
+            }
+
+            $propertyNameExtended = ($this->root instanceof VCalendar
+                                      ? 'xcal'
+                                      : 'xcard') . ':' . $propertyName;
+
+            switch ($propertyNameExtended) {
+
+                case 'xcal:geo':
+                    $propertyType               = 'float';
+                    $propertyValue['latitude']  = 0;
+                    $propertyValue['longitude'] = 0;
+
+                    foreach ($xmlProperty['value'] as $xmlRequestChild) {
+                        $propertyValue[static::getTagName($xmlRequestChild['name'])]
+                            = $xmlRequestChild['value'];
+                    }
+                    break;
+
+                case 'xcal:request-status':
+                    $propertyType = 'text';
+
+                    foreach ($xmlProperty['value'] as $xmlRequestChild) {
+                        $propertyValue[static::getTagName($xmlRequestChild['name'])]
+                            = $xmlRequestChild['value'];
+                    }
+                    break;
+
+                case 'xcal:freebusy':
+                    $propertyType = 'freebusy';
+                    // We don't break because we only want to set
+                    // another property type.
+
+                case 'xcal:categories':
+                case 'xcal:resources':
+                case 'xcal:exdate':
+                    foreach ($xmlProperty['value'] as $specialChild) {
+                        $propertyValue[static::getTagName($specialChild['name'])]
+                            = $specialChild['value'];
+                    }
+                    break;
+
+                case 'xcal:rdate':
+                    $propertyType = 'date-time';
+
+                    foreach ($xmlProperty['value'] as $specialChild) {
+
+                        $tagName = static::getTagName($specialChild['name']);
+
+                        if ('period' === $tagName) {
+
+                            $propertyParameters['value'] = 'PERIOD';
+                            $propertyValue[]             = implode('/', $specialChild['value']);
+
+                        }
+                        else {
+                            $propertyValue[] = $specialChild['value'];
+                        }
+                    }
+                    break;
+
+                default:
+                    $propertyType  = static::getTagName($xmlProperty['value'][0]['name']);
+
+                    foreach ($xmlProperty['value'] as $value) {
+                        $propertyValue[] = $value['value'];
+                    }
+
+                    if ('date' === $propertyType) {
+                        $propertyParameters['value'] = 'DATE';
+                    }
+                    break;
+            }
+
+            $this->createProperty(
+                $parentComponent,
+                $propertyNamePrefix . $propertyName,
+                $propertyParameters,
+                $propertyType,
+                $propertyValue
+            );
+
+        }
+
+    }
+
+    /**
+     * Parse a component.
+     *
+     * @param Component $parentComponent
+     *
+     * @return void
+     */
+    protected function parseComponent(Component $parentComponent) {
+
+        $components = $this->pointer['value'] ?: [];
+
+        foreach ($components as $component) {
+
+            $componentName    = static::getTagName($component['name']);
+            $currentComponent = $this->root->createComponent(
+                $componentName,
+                null,
+                false
+            );
+
+            $this->pointer = &$component;
+            $this->parseVCalendarComponents($currentComponent);
+
+            $parentComponent->add($currentComponent);
+
+        }
+
+    }
+
+    /**
+     * Create a property.
+     *
+     * @param Component $parentComponent
+     * @param string $name
+     * @param array $parameters
+     * @param string $type
+     * @param mixed $value
+     *
+     * @return void
+     */
+    protected function createProperty(Component $parentComponent, $name, $parameters, $type, $value) {
+
+        $property = $this->root->createProperty(
+            $name,
+            null,
+            $parameters,
+            $type
+        );
+        $parentComponent->add($property);
+        $property->setXmlValue($value);
+
+    }
+
+    /**
+     * Sets the input data.
+     *
+     * @param resource|string $input
+     *
+     * @return void
+     */
+    function setInput($input) {
+
+        if (is_resource($input)) {
+            $input = stream_get_contents($input);
+        }
+
+        if (is_string($input)) {
+
+            $reader = new SabreXml\Reader();
+            $reader->elementMap['{' . self::XCAL_NAMESPACE . '}period']
+                = 'Sabre\VObject\Parser\XML\Element\KeyValue';
+            $reader->elementMap['{' . self::XCAL_NAMESPACE . '}recur']
+                = 'Sabre\VObject\Parser\XML\Element\KeyValue';
+            $reader->xml($input);
+            $input  = $reader->parse();
+
+        }
+
+        $this->input = $input;
+
+    }
+
+    /**
+     * Get tag name from a Clark notation.
+     *
+     * @param string $clarkedTagName
+     *
+     * @return string
+     */
+    protected static function getTagName($clarkedTagName) {
+
+        list(, $tagName) = SabreXml\Service::parseClarkNotation($clarkedTagName);
+        return $tagName;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Parser/XML/Element/KeyValue.php b/vendor/sabre/vobject/lib/Parser/XML/Element/KeyValue.php
new file mode 100644
index 000000000..14d798433
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Parser/XML/Element/KeyValue.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Sabre\VObject\Parser\XML\Element;
+
+use Sabre\Xml as SabreXml;
+
+/**
+ * Our own sabre/xml key-value element.
+ *
+ * It just removes the clark notation.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Ivan Enderlin
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class KeyValue extends SabreXml\Element\KeyValue {
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called staticly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * Important note 2: You are responsible for advancing the reader to the
+     * next element. Not doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param XML\Reader $reader
+     *
+     * @return mixed
+     */
+    static function xmlDeserialize(SabreXml\Reader $reader) {
+
+        // If there's no children, we don't do anything.
+        if ($reader->isEmptyElement) {
+            $reader->next();
+            return [];
+        }
+
+        $values = [];
+        $reader->read();
+
+        do {
+
+            if ($reader->nodeType === SabreXml\Reader::ELEMENT) {
+
+                $name = $reader->localName;
+                $values[$name] = $reader->parseCurrentElement()['value'];
+
+            } else {
+                $reader->read();
+            }
+
+        } while ($reader->nodeType !== SabreXml\Reader::END_ELEMENT);
+
+        $reader->read();
+
+        return $values;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property.php b/vendor/sabre/vobject/lib/Property.php
new file mode 100644
index 000000000..112775131
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property.php
@@ -0,0 +1,662 @@
+<?php
+
+namespace Sabre\VObject;
+
+use Sabre\Xml;
+
+/**
+ * Property.
+ *
+ * A property is always in a KEY:VALUE structure, and may optionally contain
+ * parameters.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+abstract class Property extends Node {
+
+    /**
+     * Property name.
+     *
+     * This will contain a string such as DTSTART, SUMMARY, FN.
+     *
+     * @var string
+     */
+    public $name;
+
+    /**
+     * Property group.
+     *
+     * This is only used in vcards
+     *
+     * @var string
+     */
+    public $group;
+
+    /**
+     * List of parameters.
+     *
+     * @var array
+     */
+    public $parameters = [];
+
+    /**
+     * Current value.
+     *
+     * @var mixed
+     */
+    protected $value;
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = ';';
+
+    /**
+     * Creates the generic property.
+     *
+     * Parameters must be specified in key=>value syntax.
+     *
+     * @param Component $root The root document
+     * @param string $name
+     * @param string|array|null $value
+     * @param array $parameters List of parameters
+     * @param string $group The vcard property group
+     *
+     * @return void
+     */
+    function __construct(Component $root, $name, $value = null, array $parameters = [], $group = null) {
+
+        $this->name = $name;
+        $this->group = $group;
+
+        $this->root = $root;
+
+        foreach ($parameters as $k => $v) {
+            $this->add($k, $v);
+        }
+
+        if (!is_null($value)) {
+            $this->setValue($value);
+        }
+
+    }
+
+    /**
+     * Updates the current value.
+     *
+     * This may be either a single, or multiple strings in an array.
+     *
+     * @param string|array $value
+     *
+     * @return void
+     */
+    function setValue($value) {
+
+        $this->value = $value;
+
+    }
+
+    /**
+     * Returns the current value.
+     *
+     * This method will always return a singular value. If this was a
+     * multi-value object, some decision will be made first on how to represent
+     * it as a string.
+     *
+     * To get the correct multi-value version, use getParts.
+     *
+     * @return string
+     */
+    function getValue() {
+
+        if (is_array($this->value)) {
+            if (count($this->value) == 0) {
+                return;
+            } elseif (count($this->value) === 1) {
+                return $this->value[0];
+            } else {
+                return $this->getRawMimeDirValue();
+            }
+        } else {
+            return $this->value;
+        }
+
+    }
+
+    /**
+     * Sets a multi-valued property.
+     *
+     * @param array $parts
+     *
+     * @return void
+     */
+    function setParts(array $parts) {
+
+        $this->value = $parts;
+
+    }
+
+    /**
+     * Returns a multi-valued property.
+     *
+     * This method always returns an array, if there was only a single value,
+     * it will still be wrapped in an array.
+     *
+     * @return array
+     */
+    function getParts() {
+
+        if (is_null($this->value)) {
+            return [];
+        } elseif (is_array($this->value)) {
+            return $this->value;
+        } else {
+            return [$this->value];
+        }
+
+    }
+
+    /**
+     * Adds a new parameter.
+     *
+     * If a parameter with same name already existed, the values will be
+     * combined.
+     * If nameless parameter is added, we try to guess it's name.
+     *
+     * @param string $name
+     * @param string|null|array $value
+     */
+    function add($name, $value = null) {
+        $noName = false;
+        if ($name === null) {
+            $name = Parameter::guessParameterNameByValue($value);
+            $noName = true;
+        }
+
+        if (isset($this->parameters[strtoupper($name)])) {
+            $this->parameters[strtoupper($name)]->addValue($value);
+        }
+        else {
+            $param = new Parameter($this->root, $name, $value);
+            $param->noName = $noName;
+            $this->parameters[$param->name] = $param;
+        }
+    }
+
+    /**
+     * Returns an iterable list of children.
+     *
+     * @return array
+     */
+    function parameters() {
+
+        return $this->parameters;
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    abstract function getValueType();
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    abstract function setRawMimeDirValue($val);
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    abstract function getRawMimeDirValue();
+
+    /**
+     * Turns the object back into a serialized blob.
+     *
+     * @return string
+     */
+    function serialize() {
+
+        $str = $this->name;
+        if ($this->group) $str = $this->group . '.' . $this->name;
+
+        foreach ($this->parameters() as $param) {
+
+            $str .= ';' . $param->serialize();
+
+        }
+
+        $str .= ':' . $this->getRawMimeDirValue();
+
+        $out = '';
+        while (strlen($str) > 0) {
+            if (strlen($str) > 75) {
+                $out .= mb_strcut($str, 0, 75, 'utf-8') . "\r\n";
+                $str = ' ' . mb_strcut($str, 75, strlen($str), 'utf-8');
+            } else {
+                $out .= $str . "\r\n";
+                $str = '';
+                break;
+            }
+        }
+
+        return $out;
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for JSON.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        return $this->getParts();
+
+    }
+
+    /**
+     * Sets the JSON value, as it would appear in a jCard or jCal object.
+     *
+     * The value must always be an array.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setJsonValue(array $value) {
+
+        if (count($value) === 1) {
+            $this->setValue(reset($value));
+        } else {
+            $this->setValue($value);
+        }
+
+    }
+
+    /**
+     * This method returns an array, with the representation as it should be
+     * encoded in JSON. This is used to create jCard or jCal documents.
+     *
+     * @return array
+     */
+    function jsonSerialize() {
+
+        $parameters = [];
+
+        foreach ($this->parameters as $parameter) {
+            if ($parameter->name === 'VALUE') {
+                continue;
+            }
+            $parameters[strtolower($parameter->name)] = $parameter->jsonSerialize();
+        }
+        // In jCard, we need to encode the property-group as a separate 'group'
+        // parameter.
+        if ($this->group) {
+            $parameters['group'] = $this->group;
+        }
+
+        return array_merge(
+            [
+                strtolower($this->name),
+                (object)$parameters,
+                strtolower($this->getValueType()),
+            ],
+            $this->getJsonValue()
+        );
+    }
+
+    /**
+     * Hydrate data from a XML subtree, as it would appear in a xCard or xCal
+     * object.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setXmlValue(array $value) {
+
+        $this->setJsonValue($value);
+
+    }
+
+    /**
+     * This method serializes the data into XML. This is used to create xCard or
+     * xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    function xmlSerialize(Xml\Writer $writer) {
+
+        $parameters = [];
+
+        foreach ($this->parameters as $parameter) {
+
+            if ($parameter->name === 'VALUE') {
+                continue;
+            }
+
+            $parameters[] = $parameter;
+
+        }
+
+        $writer->startElement(strtolower($this->name));
+
+        if (!empty($parameters)) {
+
+            $writer->startElement('parameters');
+
+            foreach ($parameters as $parameter) {
+
+                $writer->startElement(strtolower($parameter->name));
+                $writer->write($parameter);
+                $writer->endElement();
+
+            }
+
+            $writer->endElement();
+
+        }
+
+        $this->xmlSerializeValue($writer);
+        $writer->endElement();
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        $valueType = strtolower($this->getValueType());
+
+        foreach ($this->getJsonValue() as $values) {
+            foreach ((array)$values as $value) {
+                $writer->writeElement($valueType, $value);
+            }
+        }
+
+    }
+
+    /**
+     * Called when this object is being cast to a string.
+     *
+     * If the property only had a single value, you will get just that. In the
+     * case the property had multiple values, the contents will be escaped and
+     * combined with ,.
+     *
+     * @return string
+     */
+    function __toString() {
+
+        return (string)$this->getValue();
+
+    }
+
+    /* ArrayAccess interface {{{ */
+
+    /**
+     * Checks if an array element exists.
+     *
+     * @param mixed $name
+     *
+     * @return bool
+     */
+    function offsetExists($name) {
+
+        if (is_int($name)) return parent::offsetExists($name);
+
+        $name = strtoupper($name);
+
+        foreach ($this->parameters as $parameter) {
+            if ($parameter->name == $name) return true;
+        }
+        return false;
+
+    }
+
+    /**
+     * Returns a parameter.
+     *
+     * If the parameter does not exist, null is returned.
+     *
+     * @param string $name
+     *
+     * @return Node
+     */
+    function offsetGet($name) {
+
+        if (is_int($name)) return parent::offsetGet($name);
+        $name = strtoupper($name);
+
+        if (!isset($this->parameters[$name])) {
+            return;
+        }
+
+        return $this->parameters[$name];
+
+    }
+
+    /**
+     * Creates a new parameter.
+     *
+     * @param string $name
+     * @param mixed $value
+     *
+     * @return void
+     */
+    function offsetSet($name, $value) {
+
+        if (is_int($name)) {
+            parent::offsetSet($name, $value);
+            // @codeCoverageIgnoreStart
+            // This will never be reached, because an exception is always
+            // thrown.
+            return;
+            // @codeCoverageIgnoreEnd
+        }
+
+        $param = new Parameter($this->root, $name, $value);
+        $this->parameters[$param->name] = $param;
+
+    }
+
+    /**
+     * Removes one or more parameters with the specified name.
+     *
+     * @param string $name
+     *
+     * @return void
+     */
+    function offsetUnset($name) {
+
+        if (is_int($name)) {
+            parent::offsetUnset($name);
+            // @codeCoverageIgnoreStart
+            // This will never be reached, because an exception is always
+            // thrown.
+            return;
+            // @codeCoverageIgnoreEnd
+        }
+
+        unset($this->parameters[strtoupper($name)]);
+
+    }
+    /* }}} */
+
+    /**
+     * This method is automatically called when the object is cloned.
+     * Specifically, this will ensure all child elements are also cloned.
+     *
+     * @return void
+     */
+    function __clone() {
+
+        foreach ($this->parameters as $key => $child) {
+            $this->parameters[$key] = clone $child;
+            $this->parameters[$key]->parent = $this;
+        }
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   - Node::REPAIR - If something is broken, and automatic repair may
+     *                    be attempted.
+     *
+     * An array is returned with warnings.
+     *
+     * Every item in the array has the following properties:
+     *    * level - (number between 1 and 3 with severity information)
+     *    * message - (human readable message)
+     *    * node - (reference to the offending node)
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $warnings = [];
+
+        // Checking if our value is UTF-8
+        if (!StringUtil::isUTF8($this->getRawMimeDirValue())) {
+
+            $oldValue = $this->getRawMimeDirValue();
+            $level = 3;
+            if ($options & self::REPAIR) {
+                $newValue = StringUtil::convertToUTF8($oldValue);
+                if (true || StringUtil::isUTF8($newValue)) {
+                    $this->setRawMimeDirValue($newValue);
+                    $level = 1;
+                }
+
+            }
+
+
+            if (preg_match('%([\x00-\x08\x0B-\x0C\x0E-\x1F\x7F])%', $oldValue, $matches)) {
+                $message = 'Property contained a control character (0x' . bin2hex($matches[1]) . ')';
+            } else {
+                $message = 'Property is not valid UTF-8! ' . $oldValue;
+            }
+
+            $warnings[] = [
+                'level'   => $level,
+                'message' => $message,
+                'node'    => $this,
+            ];
+        }
+
+        // Checking if the propertyname does not contain any invalid bytes.
+        if (!preg_match('/^([A-Z0-9-]+)$/', $this->name)) {
+            $warnings[] = [
+                'level'   => 1,
+                'message' => 'The propertyname: ' . $this->name . ' contains invalid characters. Only A-Z, 0-9 and - are allowed',
+                'node'    => $this,
+            ];
+            if ($options & self::REPAIR) {
+                // Uppercasing and converting underscores to dashes.
+                $this->name = strtoupper(
+                    str_replace('_', '-', $this->name)
+                );
+                // Removing every other invalid character
+                $this->name = preg_replace('/([^A-Z0-9-])/u', '', $this->name);
+
+            }
+
+        }
+
+        if ($encoding = $this->offsetGet('ENCODING')) {
+
+            if ($this->root->getDocumentType() === Document::VCARD40) {
+                $warnings[] = [
+                    'level'   => 1,
+                    'message' => 'ENCODING parameter is not valid in vCard 4.',
+                    'node'    => $this
+                ];
+            } else {
+
+                $encoding = (string)$encoding;
+
+                $allowedEncoding = [];
+
+                switch ($this->root->getDocumentType()) {
+                    case Document::ICALENDAR20 :
+                        $allowedEncoding = ['8BIT', 'BASE64'];
+                        break;
+                    case Document::VCARD21 :
+                        $allowedEncoding = ['QUOTED-PRINTABLE', 'BASE64', '8BIT'];
+                        break;
+                    case Document::VCARD30 :
+                        $allowedEncoding = ['B'];
+                        break;
+
+                }
+                if ($allowedEncoding && !in_array(strtoupper($encoding), $allowedEncoding)) {
+                    $warnings[] = [
+                        'level'   => 1,
+                        'message' => 'ENCODING=' . strtoupper($encoding) . ' is not valid for this document type.',
+                        'node'    => $this
+                    ];
+                }
+            }
+
+        }
+
+        // Validating inner parameters
+        foreach ($this->parameters as $param) {
+            $warnings = array_merge($warnings, $param->validate($options));
+        }
+
+        return $warnings;
+
+    }
+
+    /**
+     * Call this method on a document if you're done using it.
+     *
+     * It's intended to remove all circular references, so PHP can easily clean
+     * it up.
+     *
+     * @return void
+     */
+    function destroy() {
+
+        parent::destroy();
+        foreach ($this->parameters as $param) {
+            $param->destroy();
+        }
+        $this->parameters = [];
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/Binary.php b/vendor/sabre/vobject/lib/Property/Binary.php
new file mode 100644
index 000000000..d54cae25d
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/Binary.php
@@ -0,0 +1,128 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use Sabre\VObject\Property;
+
+/**
+ * BINARY property.
+ *
+ * This object represents BINARY values.
+ *
+ * Binary values are most commonly used by the iCalendar ATTACH property, and
+ * the vCard PHOTO property.
+ *
+ * This property will transparently encode and decode to base64.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Binary extends Property {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = null;
+
+    /**
+     * Updates the current value.
+     *
+     * This may be either a single, or multiple strings in an array.
+     *
+     * @param string|array $value
+     *
+     * @return void
+     */
+    function setValue($value) {
+
+        if (is_array($value)) {
+
+            if (count($value) === 1) {
+                $this->value = $value[0];
+            } else {
+                throw new \InvalidArgumentException('The argument must either be a string or an array with only one child');
+            }
+
+        } else {
+
+            $this->value = $value;
+
+        }
+
+    }
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->value = base64_decode($val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return base64_encode($this->value);
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'BINARY';
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        return [base64_encode($this->getValue())];
+
+    }
+
+    /**
+     * Sets the json value, as it would appear in a jCard or jCal object.
+     *
+     * The value must always be an array.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setJsonValue(array $value) {
+
+        $value = array_map('base64_decode', $value);
+        parent::setJsonValue($value);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/Boolean.php b/vendor/sabre/vobject/lib/Property/Boolean.php
new file mode 100644
index 000000000..6f5887e25
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/Boolean.php
@@ -0,0 +1,84 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use
+    Sabre\VObject\Property;
+
+/**
+ * Boolean property.
+ *
+ * This object represents BOOLEAN values. These are always the case-insenstive
+ * string TRUE or FALSE.
+ *
+ * Automatic conversion to PHP's true and false are done.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Boolean extends Property {
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $val = strtoupper($val) === 'TRUE' ? true : false;
+        $this->setValue($val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return $this->value ? 'TRUE' : 'FALSE';
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'BOOLEAN';
+
+    }
+
+    /**
+     * Hydrate data from a XML subtree, as it would appear in a xCard or xCal
+     * object.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setXmlValue(array $value) {
+
+        $value = array_map(
+            function($value) {
+                return 'true' === $value;
+            },
+            $value
+        );
+        parent::setXmlValue($value);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/FlatText.php b/vendor/sabre/vobject/lib/Property/FlatText.php
new file mode 100644
index 000000000..2c7b43c29
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/FlatText.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+/**
+ * FlatText property.
+ *
+ * This object represents certain TEXT values.
+ *
+ * Specifically, this property is used for text values where there is only 1
+ * part. Semi-colons and colons will be de-escaped when deserializing, but if
+ * any semi-colons or commas appear without a backslash, we will not assume
+ * that they are delimiters.
+ *
+ * vCard 2.1 specifically has a whole bunch of properties where this may
+ * happen, as it only defines a delimiter for a few properties.
+ *
+ * vCard 4.0 states something similar. An unescaped semi-colon _may_ be a
+ * delimiter, depending on the property.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class FlatText extends Text {
+
+    /**
+     * Field separator.
+     *
+     * @var string
+     */
+    public $delimiter = ',';
+
+    /**
+     * Sets the value as a quoted-printable encoded string.
+     *
+     * Overriding this so we're not splitting on a ; delimiter.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setQuotedPrintableValue($val) {
+
+        $val = quoted_printable_decode($val);
+        $this->setValue($val);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/FloatValue.php b/vendor/sabre/vobject/lib/Property/FloatValue.php
new file mode 100644
index 000000000..15b119549
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/FloatValue.php
@@ -0,0 +1,142 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use Sabre\VObject\Property;
+use Sabre\Xml;
+
+/**
+ * Float property.
+ *
+ * This object represents FLOAT values. These can be 1 or more floating-point
+ * numbers.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class FloatValue extends Property {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = ';';
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $val = explode($this->delimiter, $val);
+        foreach ($val as &$item) {
+            $item = (float)$item;
+        }
+        $this->setParts($val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return implode(
+            $this->delimiter,
+            $this->getParts()
+        );
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'FLOAT';
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for JSON.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $val = array_map('floatval', $this->getParts());
+
+        // Special-casing the GEO property.
+        //
+        // See:
+        // http://tools.ietf.org/html/draft-ietf-jcardcal-jcal-04#section-3.4.1.2
+        if ($this->name === 'GEO') {
+            return [$val];
+        }
+
+        return $val;
+
+    }
+
+    /**
+     * Hydrate data from a XML subtree, as it would appear in a xCard or xCal
+     * object.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setXmlValue(array $value) {
+
+        $value = array_map('floatval', $value);
+        parent::setXmlValue($value);
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        // Special-casing the GEO property.
+        //
+        // See:
+        // http://tools.ietf.org/html/rfc6321#section-3.4.1.2
+        if ($this->name === 'GEO') {
+
+            $value = array_map('floatval', $this->getParts());
+
+            $writer->writeElement('latitude', $value[0]);
+            $writer->writeElement('longitude', $value[1]);
+
+        }
+        else {
+            parent::xmlSerializeValue($writer);
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/ICalendar/CalAddress.php b/vendor/sabre/vobject/lib/Property/ICalendar/CalAddress.php
new file mode 100644
index 000000000..a0c4a9b9a
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/ICalendar/CalAddress.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace Sabre\VObject\Property\ICalendar;
+
+use
+    Sabre\VObject\Property\Text;
+
+/**
+ * CalAddress property.
+ *
+ * This object encodes CAL-ADDRESS values, as defined in rfc5545
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class CalAddress extends Text {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = null;
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'CAL-ADDRESS';
+
+    }
+
+    /**
+     * This returns a normalized form of the value.
+     *
+     * This is primarily used right now to turn mixed-cased schemes in user
+     * uris to lower-case.
+     *
+     * Evolution in particular tends to encode mailto: as MAILTO:.
+     *
+     * @return string
+     */
+    function getNormalizedValue() {
+
+        $input = $this->getValue();
+        if (!strpos($input, ':')) {
+            return $input;
+        }
+        list($schema, $everythingElse) = explode(':', $input, 2);
+        return strtolower($schema) . ':' . $everythingElse;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Property/ICalendar/Date.php b/vendor/sabre/vobject/lib/Property/ICalendar/Date.php
new file mode 100644
index 000000000..378a0d60a
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/ICalendar/Date.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Sabre\VObject\Property\ICalendar;
+
+/**
+ * DateTime property.
+ *
+ * This object represents DATE values, as defined here:
+ *
+ * http://tools.ietf.org/html/rfc5545#section-3.3.5
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Date extends DateTime {
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/ICalendar/DateTime.php b/vendor/sabre/vobject/lib/Property/ICalendar/DateTime.php
new file mode 100644
index 000000000..d580d4f68
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/ICalendar/DateTime.php
@@ -0,0 +1,404 @@
+<?php
+
+namespace Sabre\VObject\Property\ICalendar;
+
+use DateTimeInterface;
+use DateTimeZone;
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\InvalidDataException;
+use Sabre\VObject\Property;
+use Sabre\VObject\TimeZoneUtil;
+
+/**
+ * DateTime property.
+ *
+ * This object represents DATE-TIME values, as defined here:
+ *
+ * http://tools.ietf.org/html/rfc5545#section-3.3.4
+ *
+ * This particular object has a bit of hackish magic that it may also in some
+ * cases represent a DATE value. This is because it's a common usecase to be
+ * able to change a DATE-TIME into a DATE.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class DateTime extends Property {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = ',';
+
+    /**
+     * Sets a multi-valued property.
+     *
+     * You may also specify DateTime objects here.
+     *
+     * @param array $parts
+     *
+     * @return void
+     */
+    function setParts(array $parts) {
+
+        if (isset($parts[0]) && $parts[0] instanceof DateTimeInterface) {
+            $this->setDateTimes($parts);
+        } else {
+            parent::setParts($parts);
+        }
+
+    }
+
+    /**
+     * Updates the current value.
+     *
+     * This may be either a single, or multiple strings in an array.
+     *
+     * Instead of strings, you may also use DateTime here.
+     *
+     * @param string|array|DateTimeInterface $value
+     *
+     * @return void
+     */
+    function setValue($value) {
+
+        if (is_array($value) && isset($value[0]) && $value[0] instanceof DateTimeInterface) {
+            $this->setDateTimes($value);
+        } elseif ($value instanceof DateTimeInterface) {
+            $this->setDateTimes([$value]);
+        } else {
+            parent::setValue($value);
+        }
+
+    }
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue(explode($this->delimiter, $val));
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return implode($this->delimiter, $this->getParts());
+
+    }
+
+    /**
+     * Returns true if this is a DATE-TIME value, false if it's a DATE.
+     *
+     * @return bool
+     */
+    function hasTime() {
+
+        return strtoupper((string)$this['VALUE']) !== 'DATE';
+
+    }
+
+    /**
+     * Returns true if this is a floating DATE or DATE-TIME.
+     *
+     * Note that DATE is always floating.
+     */
+    function isFloating() {
+
+        return
+            !$this->hasTime() ||
+            (
+                !isset($this['TZID']) &&
+                strpos($this->getValue(), 'Z') === false
+            );
+
+    }
+
+    /**
+     * Returns a date-time value.
+     *
+     * Note that if this property contained more than 1 date-time, only the
+     * first will be returned. To get an array with multiple values, call
+     * getDateTimes.
+     *
+     * If no timezone information is known, because it's either an all-day
+     * property or floating time, we will use the DateTimeZone argument to
+     * figure out the exact date.
+     *
+     * @param DateTimeZone $timeZone
+     *
+     * @return DateTimeImmutable
+     */
+    function getDateTime(DateTimeZone $timeZone = null) {
+
+        $dt = $this->getDateTimes($timeZone);
+        if (!$dt) return;
+
+        return $dt[0];
+
+    }
+
+    /**
+     * Returns multiple date-time values.
+     *
+     * If no timezone information is known, because it's either an all-day
+     * property or floating time, we will use the DateTimeZone argument to
+     * figure out the exact date.
+     *
+     * @param DateTimeZone $timeZone
+     *
+     * @return DateTimeImmutable[]
+     * @return \DateTime[]
+     */
+    function getDateTimes(DateTimeZone $timeZone = null) {
+
+        // Does the property have a TZID?
+        $tzid = $this['TZID'];
+
+        if ($tzid) {
+            $timeZone = TimeZoneUtil::getTimeZone((string)$tzid, $this->root);
+        }
+
+        $dts = [];
+        foreach ($this->getParts() as $part) {
+            $dts[] = DateTimeParser::parse($part, $timeZone);
+        }
+        return $dts;
+
+    }
+
+    /**
+     * Sets the property as a DateTime object.
+     *
+     * @param DateTimeInterface $dt
+     * @param bool isFloating If set to true, timezones will be ignored.
+     *
+     * @return void
+     */
+    function setDateTime(DateTimeInterface $dt, $isFloating = false) {
+
+        $this->setDateTimes([$dt], $isFloating);
+
+    }
+
+    /**
+     * Sets the property as multiple date-time objects.
+     *
+     * The first value will be used as a reference for the timezones, and all
+     * the otehr values will be adjusted for that timezone
+     *
+     * @param DateTimeInterface[] $dt
+     * @param bool isFloating If set to true, timezones will be ignored.
+     *
+     * @return void
+     */
+    function setDateTimes(array $dt, $isFloating = false) {
+
+        $values = [];
+
+        if ($this->hasTime()) {
+
+            $tz = null;
+            $isUtc = false;
+
+            foreach ($dt as $d) {
+
+                if ($isFloating) {
+                    $values[] = $d->format('Ymd\\THis');
+                    continue;
+                }
+                if (is_null($tz)) {
+                    $tz = $d->getTimeZone();
+                    $isUtc = in_array($tz->getName(), ['UTC', 'GMT', 'Z', '+00:00']);
+                    if (!$isUtc) {
+                        $this->offsetSet('TZID', $tz->getName());
+                    }
+                } else {
+                    $d = $d->setTimeZone($tz);
+                }
+
+                if ($isUtc) {
+                    $values[] = $d->format('Ymd\\THis\\Z');
+                } else {
+                    $values[] = $d->format('Ymd\\THis');
+                }
+
+            }
+            if ($isUtc || $isFloating) {
+                $this->offsetUnset('TZID');
+            }
+
+        } else {
+
+            foreach ($dt as $d) {
+
+                $values[] = $d->format('Ymd');
+
+            }
+            $this->offsetUnset('TZID');
+
+        }
+
+        $this->value = $values;
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return $this->hasTime() ? 'DATE-TIME' : 'DATE';
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for JSON.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $dts = $this->getDateTimes();
+        $hasTime = $this->hasTime();
+        $isFloating = $this->isFloating();
+
+        $tz = $dts[0]->getTimeZone();
+        $isUtc = $isFloating ? false : in_array($tz->getName(), ['UTC', 'GMT', 'Z']);
+
+        return array_map(
+            function(DateTimeInterface $dt) use ($hasTime, $isUtc) {
+
+                if ($hasTime) {
+                    return $dt->format('Y-m-d\\TH:i:s') . ($isUtc ? 'Z' : '');
+                } else {
+                    return $dt->format('Y-m-d');
+                }
+
+            },
+            $dts
+        );
+
+    }
+
+    /**
+     * Sets the json value, as it would appear in a jCard or jCal object.
+     *
+     * The value must always be an array.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setJsonValue(array $value) {
+
+        // dates and times in jCal have one difference to dates and times in
+        // iCalendar. In jCal date-parts are separated by dashes, and
+        // time-parts are separated by colons. It makes sense to just remove
+        // those.
+        $this->setValue(
+            array_map(
+                function($item) {
+
+                    return strtr($item, [':' => '', '-' => '']);
+
+                },
+                $value
+            )
+        );
+
+    }
+
+    /**
+     * We need to intercept offsetSet, because it may be used to alter the
+     * VALUE from DATE-TIME to DATE or vice-versa.
+     *
+     * @param string $name
+     * @param mixed $value
+     *
+     * @return void
+     */
+    function offsetSet($name, $value) {
+
+        parent::offsetSet($name, $value);
+        if (strtoupper($name) !== 'VALUE') {
+            return;
+        }
+
+        // This will ensure that dates are correctly encoded.
+        $this->setDateTimes($this->getDateTimes());
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on)
+     *   2 - An inconsequential issue
+     *   3 - A severe issue.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $messages = parent::validate($options);
+        $valueType = $this->getValueType();
+        $values = $this->getParts();
+        try {
+            foreach ($values as $value) {
+                switch ($valueType) {
+                    case 'DATE' :
+                        DateTimeParser::parseDate($value);
+                        break;
+                    case 'DATE-TIME' :
+                        DateTimeParser::parseDateTime($value);
+                        break;
+                }
+            }
+        } catch (InvalidDataException $e) {
+            $messages[] = [
+                'level'   => 3,
+                'message' => 'The supplied value (' . $value . ') is not a correct ' . $valueType,
+                'node'    => $this,
+            ];
+        }
+        return $messages;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Property/ICalendar/Duration.php b/vendor/sabre/vobject/lib/Property/ICalendar/Duration.php
new file mode 100644
index 000000000..66d366960
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/ICalendar/Duration.php
@@ -0,0 +1,85 @@
+<?php
+
+namespace Sabre\VObject\Property\ICalendar;
+
+use Sabre\VObject\Property;
+use Sabre\VObject\DateTimeParser;
+
+/**
+ * Duration property.
+ *
+ * This object represents DURATION values, as defined here:
+ *
+ * http://tools.ietf.org/html/rfc5545#section-3.3.6
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Duration extends Property {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = ',';
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue(explode($this->delimiter, $val));
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return implode($this->delimiter, $this->getParts());
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'DURATION';
+
+    }
+
+    /**
+     * Returns a DateInterval representation of the Duration property.
+     *
+     * If the property has more than one value, only the first is returned.
+     *
+     * @return \DateInterval
+     */
+    function getDateInterval() {
+
+        $parts = $this->getParts();
+        $value = $parts[0];
+        return DateTimeParser::parseDuration($value);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/ICalendar/Period.php b/vendor/sabre/vobject/lib/Property/ICalendar/Period.php
new file mode 100644
index 000000000..a4561d929
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/ICalendar/Period.php
@@ -0,0 +1,155 @@
+<?php
+
+namespace Sabre\VObject\Property\ICalendar;
+
+use Sabre\VObject\Property;
+use Sabre\VObject\DateTimeParser;
+use Sabre\Xml;
+
+/**
+ * Period property.
+ *
+ * This object represents PERIOD values, as defined here:
+ *
+ * http://tools.ietf.org/html/rfc5545#section-3.8.2.6
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Period extends Property {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = ',';
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue(explode($this->delimiter, $val));
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return implode($this->delimiter, $this->getParts());
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'PERIOD';
+
+    }
+
+    /**
+     * Sets the json value, as it would appear in a jCard or jCal object.
+     *
+     * The value must always be an array.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setJsonValue(array $value) {
+
+        $value = array_map(
+            function($item) {
+
+                return strtr(implode('/', $item), [':' => '', '-' => '']);
+
+            },
+            $value
+        );
+        parent::setJsonValue($value);
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $return = [];
+        foreach ($this->getParts() as $item) {
+
+            list($start, $end) = explode('/', $item, 2);
+
+            $start = DateTimeParser::parseDateTime($start);
+
+            // This is a duration value.
+            if ($end[0] === 'P') {
+                $return[] = [
+                    $start->format('Y-m-d\\TH:i:s'),
+                    $end
+                ];
+            } else {
+                $end = DateTimeParser::parseDateTime($end);
+                $return[] = [
+                    $start->format('Y-m-d\\TH:i:s'),
+                    $end->format('Y-m-d\\TH:i:s'),
+                ];
+            }
+
+        }
+
+        return $return;
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        $writer->startElement(strtolower($this->getValueType()));
+        $value = $this->getJsonValue();
+        $writer->writeElement('start', $value[0][0]);
+
+        if ($value[0][1][0] === 'P') {
+            $writer->writeElement('duration', $value[0][1]);
+        }
+        else {
+            $writer->writeElement('end', $value[0][1]);
+        }
+
+        $writer->endElement();
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/ICalendar/Recur.php b/vendor/sabre/vobject/lib/Property/ICalendar/Recur.php
new file mode 100644
index 000000000..a3c36dc64
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/ICalendar/Recur.php
@@ -0,0 +1,293 @@
+<?php
+
+namespace Sabre\VObject\Property\ICalendar;
+
+use Sabre\VObject\Property;
+use Sabre\Xml;
+
+/**
+ * Recur property.
+ *
+ * This object represents RECUR properties.
+ * These values are just used for RRULE and the now deprecated EXRULE.
+ *
+ * The RRULE property may look something like this:
+ *
+ * RRULE:FREQ=MONTHLY;BYDAY=1,2,3;BYHOUR=5.
+ *
+ * This property exposes this as a key=>value array that is accessible using
+ * getParts, and may be set using setParts.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Recur extends Property {
+
+    /**
+     * Updates the current value.
+     *
+     * This may be either a single, or multiple strings in an array.
+     *
+     * @param string|array $value
+     *
+     * @return void
+     */
+    function setValue($value) {
+
+        // If we're getting the data from json, we'll be receiving an object
+        if ($value instanceof \StdClass) {
+            $value = (array)$value;
+        }
+
+        if (is_array($value)) {
+            $newVal = [];
+            foreach ($value as $k => $v) {
+
+                if (is_string($v)) {
+                    $v = strtoupper($v);
+
+                    // The value had multiple sub-values
+                    if (strpos($v, ',') !== false) {
+                        $v = explode(',', $v);
+                    }
+                    if (strcmp($k, 'until') === 0) {
+                        $v = strtr($v, [':' => '', '-' => '']);
+                    }
+                } elseif (is_array($v)) {
+                    $v = array_map('strtoupper', $v);
+                }
+
+                $newVal[strtoupper($k)] = $v;
+            }
+            $this->value = $newVal;
+        } elseif (is_string($value)) {
+            $this->value = self::stringToArray($value);
+        } else {
+            throw new \InvalidArgumentException('You must either pass a string, or a key=>value array');
+        }
+
+    }
+
+    /**
+     * Returns the current value.
+     *
+     * This method will always return a singular value. If this was a
+     * multi-value object, some decision will be made first on how to represent
+     * it as a string.
+     *
+     * To get the correct multi-value version, use getParts.
+     *
+     * @return string
+     */
+    function getValue() {
+
+        $out = [];
+        foreach ($this->value as $key => $value) {
+            $out[] = $key . '=' . (is_array($value) ? implode(',', $value) : $value);
+        }
+        return strtoupper(implode(';', $out));
+
+    }
+
+    /**
+     * Sets a multi-valued property.
+     *
+     * @param array $parts
+     * @return void
+     */
+    function setParts(array $parts) {
+
+        $this->setValue($parts);
+
+    }
+
+    /**
+     * Returns a multi-valued property.
+     *
+     * This method always returns an array, if there was only a single value,
+     * it will still be wrapped in an array.
+     *
+     * @return array
+     */
+    function getParts() {
+
+        return $this->value;
+
+    }
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue($val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return $this->getValue();
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'RECUR';
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $values = [];
+        foreach ($this->getParts() as $k => $v) {
+            if (strcmp($k, 'UNTIL') === 0) {
+                $date = new DateTime($this->root, null, $v);
+                $values[strtolower($k)] = $date->getJsonValue()[0];
+            } elseif (strcmp($k, 'COUNT') === 0) {
+                $values[strtolower($k)] = intval($v);
+            } else {
+                $values[strtolower($k)] = $v;
+            }
+        }
+        return [$values];
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        $valueType = strtolower($this->getValueType());
+
+        foreach ($this->getJsonValue() as $value) {
+            $writer->writeElement($valueType, $value);
+        }
+
+    }
+
+    /**
+     * Parses an RRULE value string, and turns it into a struct-ish array.
+     *
+     * @param string $value
+     *
+     * @return array
+     */
+    static function stringToArray($value) {
+
+        $value = strtoupper($value);
+        $newValue = [];
+        foreach (explode(';', $value) as $part) {
+
+            // Skipping empty parts.
+            if (empty($part)) {
+                continue;
+            }
+            list($partName, $partValue) = explode('=', $part);
+
+            // The value itself had multiple values..
+            if (strpos($partValue, ',') !== false) {
+                $partValue = explode(',', $partValue);
+            }
+            $newValue[$partName] = $partValue;
+
+        }
+
+        return $newValue;
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on)
+     *   2 - An inconsequential issue
+     *   3 - A severe issue.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $repair = ($options & self::REPAIR);
+
+        $warnings = parent::validate($options);
+        $values = $this->getParts();
+
+        foreach ($values as $key => $value) {
+
+            if (empty($value)) {
+                $warnings[] = [
+                    'level'   => $repair ? 3 : 1,
+                    'message' => 'Invalid value for ' . $key . ' in ' . $this->name,
+                    'node'    => $this
+                ];
+                if ($repair) {
+                    unset($values[$key]);
+                }
+            }
+
+        }
+        if (!isset($values['FREQ'])) {
+            $warnings[] = [
+                'level'   => $repair ? 3 : 1,
+                'message' => 'FREQ is required in ' . $this->name,
+                'node'    => $this
+            ];
+            if ($repair) {
+                $this->parent->remove($this);
+            }
+        }
+        if ($repair) {
+            $this->setValue($values);
+        }
+
+        return $warnings;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/IntegerValue.php b/vendor/sabre/vobject/lib/Property/IntegerValue.php
new file mode 100644
index 000000000..5bd1887fa
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/IntegerValue.php
@@ -0,0 +1,88 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use
+    Sabre\VObject\Property;
+
+/**
+ * Integer property.
+ *
+ * This object represents INTEGER values. These are always a single integer.
+ * They may be preceeded by either + or -.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class IntegerValue extends Property {
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue((int)$val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return $this->value;
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'INTEGER';
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        return [(int)$this->getValue()];
+
+    }
+
+    /**
+     * Hydrate data from a XML subtree, as it would appear in a xCard or xCal
+     * object.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setXmlValue(array $value) {
+
+        $value = array_map('intval', $value);
+        parent::setXmlValue($value);
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Property/Text.php b/vendor/sabre/vobject/lib/Property/Text.php
new file mode 100644
index 000000000..2e16ac534
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/Text.php
@@ -0,0 +1,413 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use Sabre\VObject\Property;
+use Sabre\VObject\Component;
+use Sabre\VObject\Parser\MimeDir;
+use Sabre\VObject\Document;
+use Sabre\Xml;
+
+/**
+ * Text property.
+ *
+ * This object represents TEXT values.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Text extends Property {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string
+     */
+    public $delimiter = ',';
+
+    /**
+     * List of properties that are considered 'structured'.
+     *
+     * @var array
+     */
+    protected $structuredValues = [
+        // vCard
+        'N',
+        'ADR',
+        'ORG',
+        'GENDER',
+        'CLIENTPIDMAP',
+
+        // iCalendar
+        'REQUEST-STATUS',
+    ];
+
+    /**
+     * Some text components have a minimum number of components.
+     *
+     * N must for instance be represented as 5 components, separated by ;, even
+     * if the last few components are unused.
+     *
+     * @var array
+     */
+    protected $minimumPropertyValues = [
+        'N'   => 5,
+        'ADR' => 7,
+    ];
+
+    /**
+     * Creates the property.
+     *
+     * You can specify the parameters either in key=>value syntax, in which case
+     * parameters will automatically be created, or you can just pass a list of
+     * Parameter objects.
+     *
+     * @param Component $root The root document
+     * @param string $name
+     * @param string|array|null $value
+     * @param array $parameters List of parameters
+     * @param string $group The vcard property group
+     *
+     * @return void
+     */
+    function __construct(Component $root, $name, $value = null, array $parameters = [], $group = null) {
+
+        // There's two types of multi-valued text properties:
+        // 1. multivalue properties.
+        // 2. structured value properties
+        //
+        // The former is always separated by a comma, the latter by semi-colon.
+        if (in_array($name, $this->structuredValues)) {
+            $this->delimiter = ';';
+        }
+
+        parent::__construct($root, $name, $value, $parameters, $group);
+
+    }
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue(MimeDir::unescapeValue($val, $this->delimiter));
+
+    }
+
+    /**
+     * Sets the value as a quoted-printable encoded string.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setQuotedPrintableValue($val) {
+
+        $val = quoted_printable_decode($val);
+
+        // Quoted printable only appears in vCard 2.1, and the only character
+        // that may be escaped there is ;. So we are simply splitting on just
+        // that.
+        //
+        // We also don't have to unescape \\, so all we need to look for is a ;
+        // that's not preceeded with a \.
+        $regex = '# (?<!\\\\) ; #x';
+        $matches = preg_split($regex, $val);
+        $this->setValue($matches);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        $val = $this->getParts();
+
+        if (isset($this->minimumPropertyValues[$this->name])) {
+            $val = array_pad($val, $this->minimumPropertyValues[$this->name], '');
+        }
+
+        foreach ($val as &$item) {
+
+            if (!is_array($item)) {
+                $item = [$item];
+            }
+
+            foreach ($item as &$subItem) {
+                $subItem = strtr(
+                    $subItem,
+                    [
+                        '\\' => '\\\\',
+                        ';'  => '\;',
+                        ','  => '\,',
+                        "\n" => '\n',
+                        "\r" => "",
+                    ]
+                );
+            }
+            $item = implode(',', $item);
+
+        }
+
+        return implode($this->delimiter, $val);
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        // Structured text values should always be returned as a single
+        // array-item. Multi-value text should be returned as multiple items in
+        // the top-array.
+        if (in_array($this->name, $this->structuredValues)) {
+            return [$this->getParts()];
+        }
+        return $this->getParts();
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'TEXT';
+
+    }
+
+    /**
+     * Turns the object back into a serialized blob.
+     *
+     * @return string
+     */
+    function serialize() {
+
+        // We need to kick in a special type of encoding, if it's a 2.1 vcard.
+        if ($this->root->getDocumentType() !== Document::VCARD21) {
+            return parent::serialize();
+        }
+
+        $val = $this->getParts();
+
+        if (isset($this->minimumPropertyValues[$this->name])) {
+            $val = array_pad($val, $this->minimumPropertyValues[$this->name], '');
+        }
+
+        // Imploding multiple parts into a single value, and splitting the
+        // values with ;.
+        if (count($val) > 1) {
+            foreach ($val as $k => $v) {
+                $val[$k] = str_replace(';', '\;', $v);
+            }
+            $val = implode(';', $val);
+        } else {
+            $val = $val[0];
+        }
+
+        $str = $this->name;
+        if ($this->group) $str = $this->group . '.' . $this->name;
+        foreach ($this->parameters as $param) {
+
+            if ($param->getValue() === 'QUOTED-PRINTABLE') {
+                continue;
+            }
+            $str .= ';' . $param->serialize();
+
+        }
+
+
+
+        // If the resulting value contains a \n, we must encode it as
+        // quoted-printable.
+        if (strpos($val, "\n") !== false) {
+
+            $str .= ';ENCODING=QUOTED-PRINTABLE:';
+            $lastLine = $str;
+            $out = null;
+
+            // The PHP built-in quoted-printable-encode does not correctly
+            // encode newlines for us. Specifically, the \r\n sequence must in
+            // vcards be encoded as =0D=OA and we must insert soft-newlines
+            // every 75 bytes.
+            for ($ii = 0;$ii < strlen($val);$ii++) {
+                $ord = ord($val[$ii]);
+                // These characters are encoded as themselves.
+                if ($ord >= 32 && $ord <= 126) {
+                    $lastLine .= $val[$ii];
+                } else {
+                    $lastLine .= '=' . strtoupper(bin2hex($val[$ii]));
+                }
+                if (strlen($lastLine) >= 75) {
+                    // Soft line break
+                    $out .= $lastLine . "=\r\n ";
+                    $lastLine = null;
+                }
+
+            }
+            if (!is_null($lastLine)) $out .= $lastLine . "\r\n";
+            return $out;
+
+        } else {
+            $str .= ':' . $val;
+            $out = '';
+            while (strlen($str) > 0) {
+                if (strlen($str) > 75) {
+                    $out .= mb_strcut($str, 0, 75, 'utf-8') . "\r\n";
+                    $str = ' ' . mb_strcut($str, 75, strlen($str), 'utf-8');
+                } else {
+                    $out .= $str . "\r\n";
+                    $str = '';
+                    break;
+                }
+            }
+
+            return $out;
+
+        }
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        $values = $this->getParts();
+
+        $map = function($items) use ($values, $writer) {
+            foreach ($items as $i => $item) {
+                $writer->writeElement(
+                    $item,
+                    !empty($values[$i]) ? $values[$i] : null
+                );
+            }
+        };
+
+        switch ($this->name) {
+
+            // Special-casing the REQUEST-STATUS property.
+            //
+            // See:
+            // http://tools.ietf.org/html/rfc6321#section-3.4.1.3
+            case 'REQUEST-STATUS':
+                $writer->writeElement('code', $values[0]);
+                $writer->writeElement('description', $values[1]);
+
+                if (isset($values[2])) {
+                    $writer->writeElement('data', $values[2]);
+                }
+                break;
+
+            case 'N':
+                $map([
+                    'surname',
+                    'given',
+                    'additional',
+                    'prefix',
+                    'suffix'
+                ]);
+                break;
+
+            case 'GENDER':
+                $map([
+                    'sex',
+                    'text'
+                ]);
+                break;
+
+            case 'ADR':
+                $map([
+                    'pobox',
+                    'ext',
+                    'street',
+                    'locality',
+                    'region',
+                    'code',
+                    'country'
+                ]);
+                break;
+
+            case 'CLIENTPIDMAP':
+                $map([
+                    'sourceid',
+                    'uri'
+                ]);
+                break;
+
+            default:
+                parent::xmlSerializeValue($writer);
+        }
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   - Node::REPAIR - If something is broken, and automatic repair may
+     *                    be attempted.
+     *
+     * An array is returned with warnings.
+     *
+     * Every item in the array has the following properties:
+     *    * level - (number between 1 and 3 with severity information)
+     *    * message - (human readable message)
+     *    * node - (reference to the offending node)
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $warnings = parent::validate($options);
+
+        if (isset($this->minimumPropertyValues[$this->name])) {
+
+            $minimum = $this->minimumPropertyValues[$this->name];
+            $parts = $this->getParts();
+            if (count($parts) < $minimum) {
+                $warnings[] = [
+                    'level'   => $options & self::REPAIR ? 1 : 3,
+                    'message' => 'The ' . $this->name  . ' property must have at least ' . $minimum . ' values. It only has ' . count($parts),
+                    'node'    => $this,
+                ];
+                if ($options & self::REPAIR) {
+                    $parts = array_pad($parts, $minimum, '');
+                    $this->setParts($parts);
+                }
+            }
+
+        }
+        return $warnings;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Property/Time.php b/vendor/sabre/vobject/lib/Property/Time.php
new file mode 100644
index 000000000..dbafc3b85
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/Time.php
@@ -0,0 +1,144 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use Sabre\VObject\DateTimeParser;
+
+/**
+ * Time property.
+ *
+ * This object encodes TIME values.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Time extends Text {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = null;
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'TIME';
+
+    }
+
+    /**
+     * Sets the JSON value, as it would appear in a jCard or jCal object.
+     *
+     * The value must always be an array.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setJsonValue(array $value) {
+
+        // Removing colons from value.
+        $value = str_replace(
+            ':',
+            '',
+            $value
+        );
+
+        if (count($value) === 1) {
+            $this->setValue(reset($value));
+        } else {
+            $this->setValue($value);
+        }
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $parts = DateTimeParser::parseVCardTime($this->getValue());
+        $timeStr = '';
+
+        // Hour
+        if (!is_null($parts['hour'])) {
+            $timeStr .= $parts['hour'];
+
+            if (!is_null($parts['minute'])) {
+                $timeStr .= ':';
+            }
+        } else {
+            // We know either minute or second _must_ be set, so we insert a
+            // dash for an empty value.
+            $timeStr .= '-';
+        }
+
+        // Minute
+        if (!is_null($parts['minute'])) {
+            $timeStr .= $parts['minute'];
+
+            if (!is_null($parts['second'])) {
+                $timeStr .= ':';
+            }
+        } else {
+            if (isset($parts['second'])) {
+                // Dash for empty minute
+                $timeStr .= '-';
+            }
+        }
+
+        // Second
+        if (!is_null($parts['second'])) {
+            $timeStr .= $parts['second'];
+        }
+
+        // Timezone
+        if (!is_null($parts['timezone'])) {
+            if ($parts['timezone'] === 'Z') {
+                $timeStr .= 'Z';
+            } else {
+                $timeStr .=
+                    preg_replace('/([0-9]{2})([0-9]{2})$/', '$1:$2', $parts['timezone']);
+            }
+        }
+
+        return [$timeStr];
+
+    }
+
+    /**
+     * Hydrate data from a XML subtree, as it would appear in a xCard or xCal
+     * object.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setXmlValue(array $value) {
+
+        $value = array_map(
+            function($value) {
+                return str_replace(':', '', $value);
+            },
+            $value
+        );
+        parent::setXmlValue($value);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/Unknown.php b/vendor/sabre/vobject/lib/Property/Unknown.php
new file mode 100644
index 000000000..7a3373868
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/Unknown.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+/**
+ * Unknown property.
+ *
+ * This object represents any properties not recognized by the parser.
+ * This type of value has been introduced by the jCal, jCard specs.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Unknown extends Text {
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        return [$this->getRawMimeDirValue()];
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'UNKNOWN';
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/Uri.php b/vendor/sabre/vobject/lib/Property/Uri.php
new file mode 100644
index 000000000..58e676e60
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/Uri.php
@@ -0,0 +1,122 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+use Sabre\VObject\Property;
+use Sabre\VObject\Parameter;
+
+/**
+ * URI property.
+ *
+ * This object encodes URI values. vCard 2.1 calls these URL.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Uri extends Text {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = null;
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'URI';
+
+    }
+
+    /**
+     * Returns an iterable list of children.
+     *
+     * @return array
+     */
+    function parameters() {
+
+        $parameters = parent::parameters();
+        if (!isset($parameters['VALUE']) && in_array($this->name, ['URL', 'PHOTO'])) {
+            // If we are encoding a URI value, and this URI value has no
+            // VALUE=URI parameter, we add it anyway.
+            //
+            // This is not required by any spec, but both Apple iCal and Apple
+            // AddressBook (at least in version 10.8) will trip over this if
+            // this is not set, and so it improves compatibility.
+            //
+            // See Issue #227 and #235
+            $parameters['VALUE'] = new Parameter($this->root, 'VALUE', 'URI');
+        }
+        return $parameters;
+
+    }
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        // Normally we don't need to do any type of unescaping for these
+        // properties, however.. we've noticed that Google Contacts
+        // specifically escapes the colon (:) with a blackslash. While I have
+        // no clue why they thought that was a good idea, I'm unescaping it
+        // anyway.
+        //
+        // Good thing backslashes are not allowed in urls. Makes it easy to
+        // assume that a backslash is always intended as an escape character.
+        if ($this->name === 'URL') {
+            $regex = '#  (?: (\\\\ (?: \\\\ | : ) ) ) #x';
+            $matches = preg_split($regex, $val, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+            $newVal = '';
+            foreach ($matches as $match) {
+                switch ($match) {
+                    case '\:' :
+                        $newVal .= ':';
+                        break;
+                    default :
+                        $newVal .= $match;
+                        break;
+                }
+            }
+            $this->value = $newVal;
+        } else {
+            $this->value = strtr($val, ['\,' => ',']);
+        }
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        if (is_array($this->value)) {
+            $value = $this->value[0];
+        } else {
+            $value = $this->value;
+        }
+
+        return strtr($value, [',' => '\,']);
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/UtcOffset.php b/vendor/sabre/vobject/lib/Property/UtcOffset.php
new file mode 100644
index 000000000..61895c48e
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/UtcOffset.php
@@ -0,0 +1,77 @@
+<?php
+
+namespace Sabre\VObject\Property;
+
+/**
+ * UtcOffset property.
+ *
+ * This object encodes UTC-OFFSET values.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class UtcOffset extends Text {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = null;
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'UTC-OFFSET';
+
+    }
+
+    /**
+     * Sets the JSON value, as it would appear in a jCard or jCal object.
+     *
+     * The value must always be an array.
+     *
+     * @param array $value
+     *
+     * @return void
+     */
+    function setJsonValue(array $value) {
+
+        $value = array_map(
+            function($value) {
+                return str_replace(':', '', $value);
+            },
+            $value
+        );
+        parent::setJsonValue($value);
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for JSON.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        return array_map(
+            function($value) {
+                return substr($value, 0, -2) . ':' .
+                       substr($value, -2);
+            },
+            parent::getJsonValue()
+        );
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Property/VCard/Date.php b/vendor/sabre/vobject/lib/Property/VCard/Date.php
new file mode 100644
index 000000000..1ef6dff34
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/VCard/Date.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Sabre\VObject\Property\VCard;
+
+/**
+ * Date property.
+ *
+ * This object encodes vCard DATE values.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Date extends DateAndOrTime {
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'DATE';
+
+    }
+
+    /**
+     * Sets the property as a DateTime object.
+     *
+     * @param \DateTimeInterface $dt
+     *
+     * @return void
+     */
+    function setDateTime(\DateTimeInterface $dt) {
+
+        $this->value = $dt->format('Ymd');
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/VCard/DateAndOrTime.php b/vendor/sabre/vobject/lib/Property/VCard/DateAndOrTime.php
new file mode 100644
index 000000000..650e19cbf
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/VCard/DateAndOrTime.php
@@ -0,0 +1,405 @@
+<?php
+
+namespace Sabre\VObject\Property\VCard;
+
+use DateTimeInterface;
+use DateTimeImmutable;
+use DateTime;
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\InvalidDataException;
+use Sabre\VObject\Property;
+use Sabre\Xml;
+
+/**
+ * DateAndOrTime property.
+ *
+ * This object encodes DATE-AND-OR-TIME values.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class DateAndOrTime extends Property {
+
+    /**
+     * Field separator.
+     *
+     * @var null|string
+     */
+    public $delimiter = null;
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'DATE-AND-OR-TIME';
+
+    }
+
+    /**
+     * Sets a multi-valued property.
+     *
+     * You may also specify DateTime objects here.
+     *
+     * @param array $parts
+     *
+     * @return void
+     */
+    function setParts(array $parts) {
+
+        if (count($parts) > 1) {
+            throw new \InvalidArgumentException('Only one value allowed');
+        }
+        if (isset($parts[0]) && $parts[0] instanceof \DateTime) {
+            $this->setDateTime($parts[0]);
+        } else {
+            parent::setParts($parts);
+        }
+
+    }
+
+    /**
+     * Updates the current value.
+     *
+     * This may be either a single, or multiple strings in an array.
+     *
+     * Instead of strings, you may also use DateTime here.
+     *
+     * @param string|array|\DateTime $value
+     *
+     * @return void
+     */
+    function setValue($value) {
+
+        if ($value instanceof \DateTime) {
+            $this->setDateTime($value);
+        } else {
+            parent::setValue($value);
+        }
+
+    }
+
+    /**
+     * Sets the property as a DateTime object.
+     *
+     * @param DateTimeInterface $dt
+     *
+     * @return void
+     */
+    function setDateTime(DateTimeInterface $dt) {
+
+        $tz = $dt->getTimeZone();
+        $isUtc = in_array($tz->getName(), ['UTC', 'GMT', 'Z']);
+
+        if ($isUtc) {
+            $value = $dt->format('Ymd\\THis\\Z');
+        } else {
+            // Calculating the offset.
+            $value = $dt->format('Ymd\\THisO');
+        }
+
+        $this->value = $value;
+
+    }
+
+    /**
+     * Returns a date-time value.
+     *
+     * Note that if this property contained more than 1 date-time, only the
+     * first will be returned. To get an array with multiple values, call
+     * getDateTimes.
+     *
+     * If no time was specified, we will always use midnight (in the default
+     * timezone) as the time.
+     *
+     * If parts of the date were omitted, such as the year, we will grab the
+     * current values for those. So at the time of writing, if the year was
+     * omitted, we would have filled in 2014.
+     *
+     * @return DateTimeImmutable
+     */
+    function getDateTime() {
+
+        $now = new DateTime();
+
+        $tzFormat = $now->getTimezone()->getOffset($now) === 0 ? '\\Z' : 'O';
+        $nowParts = DateTimeParser::parseVCardDateTime($now->format('Ymd\\This' . $tzFormat));
+
+        $dateParts = DateTimeParser::parseVCardDateTime($this->getValue());
+
+        // This sets all the missing parts to the current date/time.
+        // So if the year was missing for a birthday, we're making it 'this
+        // year'.
+        foreach ($dateParts as $k => $v) {
+            if (is_null($v)) {
+                $dateParts[$k] = $nowParts[$k];
+            }
+        }
+        return new DateTimeImmutable("$dateParts[year]-$dateParts[month]-$dateParts[date] $dateParts[hour]:$dateParts[minute]:$dateParts[second] $dateParts[timezone]");
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $parts = DateTimeParser::parseVCardDateTime($this->getValue());
+
+        $dateStr = '';
+
+        // Year
+        if (!is_null($parts['year'])) {
+
+            $dateStr .= $parts['year'];
+
+            if (!is_null($parts['month'])) {
+                // If a year and a month is set, we need to insert a separator
+                // dash.
+                $dateStr .= '-';
+            }
+
+        } else {
+
+            if (!is_null($parts['month']) || !is_null($parts['date'])) {
+                // Inserting two dashes
+                $dateStr .= '--';
+            }
+
+        }
+
+        // Month
+        if (!is_null($parts['month'])) {
+
+            $dateStr .= $parts['month'];
+
+            if (isset($parts['date'])) {
+                // If month and date are set, we need the separator dash.
+                $dateStr .= '-';
+            }
+
+        } elseif (isset($parts['date'])) {
+            // If the month is empty, and a date is set, we need a 'empty
+            // dash'
+            $dateStr .= '-';
+        }
+
+        // Date
+        if (!is_null($parts['date'])) {
+            $dateStr .= $parts['date'];
+        }
+
+
+        // Early exit if we don't have a time string.
+        if (is_null($parts['hour']) && is_null($parts['minute']) && is_null($parts['second'])) {
+            return [$dateStr];
+        }
+
+        $dateStr .= 'T';
+
+        // Hour
+        if (!is_null($parts['hour'])) {
+
+            $dateStr .= $parts['hour'];
+
+            if (!is_null($parts['minute'])) {
+                $dateStr .= ':';
+            }
+
+        } else {
+            // We know either minute or second _must_ be set, so we insert a
+            // dash for an empty value.
+            $dateStr .= '-';
+        }
+
+        // Minute
+        if (!is_null($parts['minute'])) {
+
+            $dateStr .= $parts['minute'];
+
+            if (!is_null($parts['second'])) {
+                $dateStr .= ':';
+            }
+
+        } elseif (isset($parts['second'])) {
+            // Dash for empty minute
+            $dateStr .= '-';
+        }
+
+        // Second
+        if (!is_null($parts['second'])) {
+            $dateStr .= $parts['second'];
+        }
+
+        // Timezone
+        if (!is_null($parts['timezone'])) {
+            $dateStr .= $parts['timezone'];
+        }
+
+        return [$dateStr];
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        $valueType = strtolower($this->getValueType());
+        $parts     = DateTimeParser::parseVCardDateAndOrTime($this->getValue());
+        $value     = '';
+
+        // $d = defined
+        $d = function($part) use ($parts) {
+            return !is_null($parts[$part]);
+        };
+
+        // $r = read
+        $r = function($part) use ($parts) {
+            return $parts[$part];
+        };
+
+        // From the Relax NG Schema.
+        //
+        // # 4.3.1
+        // value-date = element date {
+        //     xsd:string { pattern = "\d{8}|\d{4}-\d\d|--\d\d(\d\d)?|---\d\d" }
+        //   }
+        if (($d('year') ||  $d('month')  ||  $d('date'))
+            && (!$d('hour') && !$d('minute') && !$d('second') && !$d('timezone'))) {
+
+            if ($d('year') && $d('month') && $d('date')) {
+                $value .= $r('year') . $r('month') . $r('date');
+            } elseif ($d('year') && $d('month') && !$d('date')) {
+                $value .= $r('year') . '-' . $r('month');
+            } elseif (!$d('year') && $d('month')) {
+                $value .= '--' . $r('month') . $r('date');
+            } elseif (!$d('year') && !$d('month') && $d('date')) {
+                $value .= '---' . $r('date');
+            }
+
+        // # 4.3.2
+        // value-time = element time {
+        //     xsd:string { pattern = "(\d\d(\d\d(\d\d)?)?|-\d\d(\d\d?)|--\d\d)"
+        //                          ~ "(Z|[+\-]\d\d(\d\d)?)?" }
+        //   }
+        } elseif ((!$d('year') && !$d('month')  && !$d('date'))
+                  && ($d('hour') ||  $d('minute') ||  $d('second'))) {
+
+            if ($d('hour')) {
+                $value .= $r('hour') . $r('minute') . $r('second');
+            } elseif ($d('minute')) {
+                $value .= '-' . $r('minute') . $r('second');
+            } elseif ($d('second')) {
+                $value .= '--' . $r('second');
+            }
+
+            $value .= $r('timezone');
+
+        // # 4.3.3
+        // value-date-time = element date-time {
+        //     xsd:string { pattern = "(\d{8}|--\d{4}|---\d\d)T\d\d(\d\d(\d\d)?)?"
+        //                          ~ "(Z|[+\-]\d\d(\d\d)?)?" }
+        //   }
+        } elseif ($d('date') && $d('hour')) {
+
+            if ($d('year') && $d('month') && $d('date')) {
+                $value .= $r('year') . $r('month') . $r('date');
+            } elseif (!$d('year') && $d('month') && $d('date')) {
+                $value .= '--' . $r('month') . $r('date');
+            } elseif (!$d('year') && !$d('month') && $d('date')) {
+                $value .= '---' . $r('date');
+            }
+
+            $value .= 'T' . $r('hour') . $r('minute') . $r('second') .
+                      $r('timezone');
+
+        }
+
+        $writer->writeElement($valueType, $value);
+
+    }
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue($val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return implode($this->delimiter, $this->getParts());
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     *
+     * The following options are supported:
+     *   Node::REPAIR - May attempt to automatically repair the problem.
+     *
+     * This method returns an array with detected problems.
+     * Every element has the following properties:
+     *
+     *  * level - problem level.
+     *  * message - A human-readable string describing the issue.
+     *  * node - A reference to the problematic node.
+     *
+     * The level means:
+     *   1 - The issue was repaired (only happens if REPAIR was turned on)
+     *   2 - An inconsequential issue
+     *   3 - A severe issue.
+     *
+     * @param int $options
+     *
+     * @return array
+     */
+    function validate($options = 0) {
+
+        $messages = parent::validate($options);
+        $value = $this->getValue();
+
+        try {
+            DateTimeParser::parseVCardDateTime($value);
+        } catch (InvalidDataException $e) {
+            $messages[] = [
+                'level'   => 3,
+                'message' => 'The supplied value (' . $value . ') is not a correct DATE-AND-OR-TIME property',
+                'node'    => $this,
+            ];
+        }
+
+        return $messages;
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Property/VCard/DateTime.php b/vendor/sabre/vobject/lib/Property/VCard/DateTime.php
new file mode 100644
index 000000000..e7c804ca7
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/VCard/DateTime.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace Sabre\VObject\Property\VCard;
+
+/**
+ * DateTime property.
+ *
+ * This object encodes DATE-TIME values for vCards.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class DateTime extends DateAndOrTime {
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'DATE-TIME';
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/VCard/LanguageTag.php b/vendor/sabre/vobject/lib/Property/VCard/LanguageTag.php
new file mode 100644
index 000000000..aa7e9178d
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/VCard/LanguageTag.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace Sabre\VObject\Property\VCard;
+
+use
+    Sabre\VObject\Property;
+
+/**
+ * LanguageTag property.
+ *
+ * This object represents LANGUAGE-TAG values as used in vCards.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class LanguageTag extends Property {
+
+    /**
+     * Sets a raw value coming from a mimedir (iCalendar/vCard) file.
+     *
+     * This has been 'unfolded', so only 1 line will be passed. Unescaping is
+     * not yet done, but parameters are not included.
+     *
+     * @param string $val
+     *
+     * @return void
+     */
+    function setRawMimeDirValue($val) {
+
+        $this->setValue($val);
+
+    }
+
+    /**
+     * Returns a raw mime-dir representation of the value.
+     *
+     * @return string
+     */
+    function getRawMimeDirValue() {
+
+        return $this->getValue();
+
+    }
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'LANGUAGE-TAG';
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Property/VCard/TimeStamp.php b/vendor/sabre/vobject/lib/Property/VCard/TimeStamp.php
new file mode 100644
index 000000000..9d311f99d
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Property/VCard/TimeStamp.php
@@ -0,0 +1,86 @@
+<?php
+
+namespace Sabre\VObject\Property\VCard;
+
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\Property\Text;
+use Sabre\Xml;
+
+/**
+ * TimeStamp property.
+ *
+ * This object encodes TIMESTAMP values.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class TimeStamp extends Text {
+
+    /**
+     * In case this is a multi-value property. This string will be used as a
+     * delimiter.
+     *
+     * @var string|null
+     */
+    public $delimiter = null;
+
+    /**
+     * Returns the type of value.
+     *
+     * This corresponds to the VALUE= parameter. Every property also has a
+     * 'default' valueType.
+     *
+     * @return string
+     */
+    function getValueType() {
+
+        return 'TIMESTAMP';
+
+    }
+
+    /**
+     * Returns the value, in the format it should be encoded for json.
+     *
+     * This method must always return an array.
+     *
+     * @return array
+     */
+    function getJsonValue() {
+
+        $parts = DateTimeParser::parseVCardDateTime($this->getValue());
+
+        $dateStr =
+            $parts['year'] . '-' .
+            $parts['month'] . '-' .
+            $parts['date'] . 'T' .
+            $parts['hour'] . ':' .
+            $parts['minute'] . ':' .
+            $parts['second'];
+
+        // Timezone
+        if (!is_null($parts['timezone'])) {
+            $dateStr .= $parts['timezone'];
+        }
+
+        return [$dateStr];
+
+    }
+
+    /**
+     * This method serializes only the value of a property. This is used to
+     * create xCard or xCal documents.
+     *
+     * @param Xml\Writer $writer  XML writer.
+     *
+     * @return void
+     */
+    protected function xmlSerializeValue(Xml\Writer $writer) {
+
+        // xCard is the only XML and JSON format that has the same date and time
+        // format than vCard.
+        $valueType = strtolower($this->getValueType());
+        $writer->writeElement($valueType, $this->getValue());
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Reader.php b/vendor/sabre/vobject/lib/Reader.php
new file mode 100644
index 000000000..709929337
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Reader.php
@@ -0,0 +1,98 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * iCalendar/vCard/jCal/jCard/xCal/xCard reader object.
+ *
+ * This object provides a few (static) convenience methods to quickly access
+ * the parsers.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Reader {
+
+    /**
+     * If this option is passed to the reader, it will be less strict about the
+     * validity of the lines.
+     */
+    const OPTION_FORGIVING = 1;
+
+    /**
+     * If this option is turned on, any lines we cannot parse will be ignored
+     * by the reader.
+     */
+    const OPTION_IGNORE_INVALID_LINES = 2;
+
+    /**
+     * Parses a vCard or iCalendar object, and returns the top component.
+     *
+     * The options argument is a bitfield. Pass any of the OPTIONS constant to
+     * alter the parsers' behaviour.
+     *
+     * You can either supply a string, or a readable stream for input.
+     *
+     * @param string|resource $data
+     * @param int $options
+     * @param string $charset
+     * @return Document
+     */
+    static function read($data, $options = 0, $charset = 'UTF-8') {
+
+        $parser = new Parser\MimeDir();
+        $parser->setCharset($charset);
+        $result = $parser->parse($data, $options);
+
+        return $result;
+
+    }
+
+    /**
+     * Parses a jCard or jCal object, and returns the top component.
+     *
+     * The options argument is a bitfield. Pass any of the OPTIONS constant to
+     * alter the parsers' behaviour.
+     *
+     * You can either a string, a readable stream, or an array for it's input.
+     * Specifying the array is useful if json_decode was already called on the
+     * input.
+     *
+     * @param string|resource|array $data
+     * @param int $options
+     *
+     * @return Document
+     */
+    static function readJson($data, $options = 0) {
+
+        $parser = new Parser\Json();
+        $result = $parser->parse($data, $options);
+
+        return $result;
+
+    }
+
+    /**
+     * Parses a xCard or xCal object, and returns the top component.
+     *
+     * The options argument is a bitfield. Pass any of the OPTIONS constant to
+     * alter the parsers' behaviour.
+     *
+     * You can either supply a string, or a readable stream for input.
+     *
+     * @param string|resource $data
+     * @param int $options
+     *
+     * @return Document
+     */
+    static function readXML($data, $options = 0) {
+
+        $parser = new Parser\XML();
+        $result = $parser->parse($data, $options);
+
+        return $result;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/Recur/EventIterator.php b/vendor/sabre/vobject/lib/Recur/EventIterator.php
new file mode 100644
index 000000000..86c996aec
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Recur/EventIterator.php
@@ -0,0 +1,507 @@
+<?php
+
+namespace Sabre\VObject\Recur;
+
+use DateTimeZone;
+use DateTimeImmutable;
+use DateTimeInterface;
+use InvalidArgumentException;
+use Sabre\VObject\Component;
+use Sabre\VObject\Component\VEvent;
+use Sabre\VObject\Settings;
+
+/**
+ * This class is used to determine new for a recurring event, when the next
+ * events occur.
+ *
+ * This iterator may loop infinitely in the future, therefore it is important
+ * that if you use this class, you set hard limits for the amount of iterations
+ * you want to handle.
+ *
+ * Note that currently there is not full support for the entire iCalendar
+ * specification, as it's very complex and contains a lot of permutations
+ * that's not yet used very often in software.
+ *
+ * For the focus has been on features as they actually appear in Calendaring
+ * software, but this may well get expanded as needed / on demand
+ *
+ * The following RRULE properties are supported
+ *   * UNTIL
+ *   * INTERVAL
+ *   * COUNT
+ *   * FREQ=DAILY
+ *     * BYDAY
+ *     * BYHOUR
+ *     * BYMONTH
+ *   * FREQ=WEEKLY
+ *     * BYDAY
+ *     * BYHOUR
+ *     * WKST
+ *   * FREQ=MONTHLY
+ *     * BYMONTHDAY
+ *     * BYDAY
+ *     * BYSETPOS
+ *   * FREQ=YEARLY
+ *     * BYMONTH
+ *     * BYMONTHDAY (only if BYMONTH is also set)
+ *     * BYDAY (only if BYMONTH is also set)
+ *
+ * Anything beyond this is 'undefined', which means that it may get ignored, or
+ * you may get unexpected results. The effect is that in some applications the
+ * specified recurrence may look incorrect, or is missing.
+ *
+ * The recurrence iterator also does not yet support THISANDFUTURE.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class EventIterator implements \Iterator {
+
+    /**
+     * Reference timeZone for floating dates and times.
+     *
+     * @var DateTimeZone
+     */
+    protected $timeZone;
+
+    /**
+     * True if we're iterating an all-day event.
+     *
+     * @var bool
+     */
+    protected $allDay = false;
+
+    /**
+     * Creates the iterator.
+     *
+     * There's three ways to set up the iterator.
+     *
+     * 1. You can pass a VCALENDAR component and a UID.
+     * 2. You can pass an array of VEVENTs (all UIDS should match).
+     * 3. You can pass a single VEVENT component.
+     *
+     * Only the second method is recomended. The other 1 and 3 will be removed
+     * at some point in the future.
+     *
+     * The $uid parameter is only required for the first method.
+     *
+     * @param Component|array $input
+     * @param string|null $uid
+     * @param DateTimeZone $timeZone Reference timezone for floating dates and
+     *                               times.
+     */
+    function __construct($input, $uid = null, DateTimeZone $timeZone = null) {
+
+        if (is_null($timeZone)) {
+            $timeZone = new DateTimeZone('UTC');
+        }
+        $this->timeZone = $timeZone;
+
+        if (is_array($input)) {
+            $events = $input;
+        } elseif ($input instanceof VEvent) {
+            // Single instance mode.
+            $events = [$input];
+        } else {
+            // Calendar + UID mode.
+            $uid = (string)$uid;
+            if (!$uid) {
+                throw new InvalidArgumentException('The UID argument is required when a VCALENDAR is passed to this constructor');
+            }
+            if (!isset($input->VEVENT)) {
+                throw new InvalidArgumentException('No events found in this calendar');
+            }
+            $events = $input->getByUID($uid);
+
+        }
+
+        foreach ($events as $vevent) {
+
+            if (!isset($vevent->{'RECURRENCE-ID'})) {
+
+                $this->masterEvent = $vevent;
+
+            } else {
+
+                $this->exceptions[
+                    $vevent->{'RECURRENCE-ID'}->getDateTime($this->timeZone)->getTimeStamp()
+                ] = true;
+                $this->overriddenEvents[] = $vevent;
+
+            }
+
+        }
+
+        if (!$this->masterEvent) {
+            // No base event was found. CalDAV does allow cases where only
+            // overridden instances are stored.
+            //
+            // In this particular case, we're just going to grab the first
+            // event and use that instead. This may not always give the
+            // desired result.
+            if (!count($this->overriddenEvents)) {
+                throw new InvalidArgumentException('This VCALENDAR did not have an event with UID: ' . $uid);
+            }
+            $this->masterEvent = array_shift($this->overriddenEvents);
+        }
+
+        $this->startDate = $this->masterEvent->DTSTART->getDateTime($this->timeZone);
+        $this->allDay = !$this->masterEvent->DTSTART->hasTime();
+
+        if (isset($this->masterEvent->EXDATE)) {
+
+            foreach ($this->masterEvent->EXDATE as $exDate) {
+
+                foreach ($exDate->getDateTimes($this->timeZone) as $dt) {
+                    $this->exceptions[$dt->getTimeStamp()] = true;
+                }
+
+            }
+
+        }
+
+        if (isset($this->masterEvent->DTEND)) {
+            $this->eventDuration =
+                $this->masterEvent->DTEND->getDateTime($this->timeZone)->getTimeStamp() -
+                $this->startDate->getTimeStamp();
+        } elseif (isset($this->masterEvent->DURATION)) {
+            $duration = $this->masterEvent->DURATION->getDateInterval();
+            $end = clone $this->startDate;
+            $end = $end->add($duration);
+            $this->eventDuration = $end->getTimeStamp() - $this->startDate->getTimeStamp();
+        } elseif ($this->allDay) {
+            $this->eventDuration = 3600 * 24;
+        } else {
+            $this->eventDuration = 0;
+        }
+
+        if (isset($this->masterEvent->RDATE)) {
+            $this->recurIterator = new RDateIterator(
+                $this->masterEvent->RDATE->getParts(),
+                $this->startDate
+            );
+        } elseif (isset($this->masterEvent->RRULE)) {
+            $this->recurIterator = new RRuleIterator(
+                $this->masterEvent->RRULE->getParts(),
+                $this->startDate
+            );
+        } else {
+            $this->recurIterator = new RRuleIterator(
+                [
+                    'FREQ'  => 'DAILY',
+                    'COUNT' => 1,
+                ],
+                $this->startDate
+            );
+        }
+
+        $this->rewind();
+        if (!$this->valid()) {
+            throw new NoInstancesException('This recurrence rule does not generate any valid instances');
+        }
+
+    }
+
+    /**
+     * Returns the date for the current position of the iterator.
+     *
+     * @return DateTimeImmutable
+     */
+    function current() {
+
+        if ($this->currentDate) {
+            return clone $this->currentDate;
+        }
+
+    }
+
+    /**
+     * This method returns the start date for the current iteration of the
+     * event.
+     *
+     * @return DateTimeImmutable
+     */
+    function getDtStart() {
+
+        if ($this->currentDate) {
+            return clone $this->currentDate;
+        }
+
+    }
+
+    /**
+     * This method returns the end date for the current iteration of the
+     * event.
+     *
+     * @return DateTimeImmutable
+     */
+    function getDtEnd() {
+
+        if (!$this->valid()) {
+            return;
+        }
+        $end = clone $this->currentDate;
+        return $end->modify('+' . $this->eventDuration . ' seconds');
+
+    }
+
+    /**
+     * Returns a VEVENT for the current iterations of the event.
+     *
+     * This VEVENT will have a recurrence id, and it's DTSTART and DTEND
+     * altered.
+     *
+     * @return VEvent
+     */
+    function getEventObject() {
+
+        if ($this->currentOverriddenEvent) {
+            return $this->currentOverriddenEvent;
+        }
+
+        $event = clone $this->masterEvent;
+
+        // Ignoring the following block, because PHPUnit's code coverage
+        // ignores most of these lines, and this messes with our stats.
+        //
+        // @codeCoverageIgnoreStart
+        unset(
+            $event->RRULE,
+            $event->EXDATE,
+            $event->RDATE,
+            $event->EXRULE,
+            $event->{'RECURRENCE-ID'}
+        );
+        // @codeCoverageIgnoreEnd
+
+        $event->DTSTART->setDateTime($this->getDtStart(), $event->DTSTART->isFloating());
+        if (isset($event->DTEND)) {
+            $event->DTEND->setDateTime($this->getDtEnd(), $event->DTEND->isFloating());
+        }
+        $recurid = clone $event->DTSTART;
+        $recurid->name = 'RECURRENCE-ID';
+        $event->add($recurid);
+        return $event;
+
+    }
+
+    /**
+     * Returns the current position of the iterator.
+     *
+     * This is for us simply a 0-based index.
+     *
+     * @return int
+     */
+    function key() {
+
+        // The counter is always 1 ahead.
+        return $this->counter - 1;
+
+    }
+
+    /**
+     * This is called after next, to see if the iterator is still at a valid
+     * position, or if it's at the end.
+     *
+     * @return bool
+     */
+    function valid() {
+
+        if ($this->counter > Settings::$maxRecurrences && Settings::$maxRecurrences !== -1) {
+            throw new MaxInstancesExceededException('Recurring events are only allowed to generate ' . Settings::$maxRecurrences);
+        }
+        return !!$this->currentDate;
+
+    }
+
+    /**
+     * Sets the iterator back to the starting point.
+     */
+    function rewind() {
+
+        $this->recurIterator->rewind();
+        // re-creating overridden event index.
+        $index = [];
+        foreach ($this->overriddenEvents as $key => $event) {
+            $stamp = $event->DTSTART->getDateTime($this->timeZone)->getTimeStamp();
+            $index[$stamp] = $key;
+        }
+        krsort($index);
+        $this->counter = 0;
+        $this->overriddenEventsIndex = $index;
+        $this->currentOverriddenEvent = null;
+
+        $this->nextDate = null;
+        $this->currentDate = clone $this->startDate;
+
+        $this->next();
+
+    }
+
+    /**
+     * Advances the iterator with one step.
+     *
+     * @return void
+     */
+    function next() {
+
+        $this->currentOverriddenEvent = null;
+        $this->counter++;
+        if ($this->nextDate) {
+            // We had a stored value.
+            $nextDate = $this->nextDate;
+            $this->nextDate = null;
+        } else {
+            // We need to ask rruleparser for the next date.
+            // We need to do this until we find a date that's not in the
+            // exception list.
+            do {
+                if (!$this->recurIterator->valid()) {
+                    $nextDate = null;
+                    break;
+                }
+                $nextDate = $this->recurIterator->current();
+                $this->recurIterator->next();
+            } while (isset($this->exceptions[$nextDate->getTimeStamp()]));
+
+        }
+
+
+        // $nextDate now contains what rrule thinks is the next one, but an
+        // overridden event may cut ahead.
+        if ($this->overriddenEventsIndex) {
+
+            $offset = end($this->overriddenEventsIndex);
+            $timestamp = key($this->overriddenEventsIndex);
+            if (!$nextDate || $timestamp < $nextDate->getTimeStamp()) {
+                // Overridden event comes first.
+                $this->currentOverriddenEvent = $this->overriddenEvents[$offset];
+
+                // Putting the rrule next date aside.
+                $this->nextDate = $nextDate;
+                $this->currentDate = $this->currentOverriddenEvent->DTSTART->getDateTime($this->timeZone);
+
+                // Ensuring that this item will only be used once.
+                array_pop($this->overriddenEventsIndex);
+
+                // Exit point!
+                return;
+
+            }
+
+        }
+
+        $this->currentDate = $nextDate;
+
+    }
+
+    /**
+     * Quickly jump to a date in the future.
+     *
+     * @param DateTimeInterface $dateTime
+     */
+    function fastForward(DateTimeInterface $dateTime) {
+
+        while ($this->valid() && $this->getDtEnd() < $dateTime) {
+            $this->next();
+        }
+
+    }
+
+    /**
+     * Returns true if this recurring event never ends.
+     *
+     * @return bool
+     */
+    function isInfinite() {
+
+        return $this->recurIterator->isInfinite();
+
+    }
+
+    /**
+     * RRULE parser.
+     *
+     * @var RRuleIterator
+     */
+    protected $recurIterator;
+
+    /**
+     * The duration, in seconds, of the master event.
+     *
+     * We use this to calculate the DTEND for subsequent events.
+     */
+    protected $eventDuration;
+
+    /**
+     * A reference to the main (master) event.
+     *
+     * @var VEVENT
+     */
+    protected $masterEvent;
+
+    /**
+     * List of overridden events.
+     *
+     * @var array
+     */
+    protected $overriddenEvents = [];
+
+    /**
+     * Overridden event index.
+     *
+     * Key is timestamp, value is the index of the item in the $overriddenEvent
+     * property.
+     *
+     * @var array
+     */
+    protected $overriddenEventsIndex;
+
+    /**
+     * A list of recurrence-id's that are either part of EXDATE, or are
+     * overridden.
+     *
+     * @var array
+     */
+    protected $exceptions = [];
+
+    /**
+     * Internal event counter.
+     *
+     * @var int
+     */
+    protected $counter;
+
+    /**
+     * The very start of the iteration process.
+     *
+     * @var DateTimeImmutable
+     */
+    protected $startDate;
+
+    /**
+     * Where we are currently in the iteration process.
+     *
+     * @var DateTimeImmutable
+     */
+    protected $currentDate;
+
+    /**
+     * The next date from the rrule parser.
+     *
+     * Sometimes we need to temporary store the next date, because an
+     * overridden event came before.
+     *
+     * @var DateTimeImmutable
+     */
+    protected $nextDate;
+
+    /**
+     * The event that overwrites the current iteration
+     *
+     * @var VEVENT
+     */
+    protected $currentOverriddenEvent;
+
+}
diff --git a/vendor/sabre/vobject/lib/Recur/MaxInstancesExceededException.php b/vendor/sabre/vobject/lib/Recur/MaxInstancesExceededException.php
new file mode 100644
index 000000000..264df7d2b
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Recur/MaxInstancesExceededException.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Sabre\VObject\Recur;
+
+use Exception;
+
+/**
+ * This exception will get thrown when a recurrence rule generated more than
+ * the maximum number of instances.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ */
+class MaxInstancesExceededException extends Exception {
+}
diff --git a/vendor/sabre/vobject/lib/Recur/NoInstancesException.php b/vendor/sabre/vobject/lib/Recur/NoInstancesException.php
new file mode 100644
index 000000000..8f8bb472b
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Recur/NoInstancesException.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Sabre\VObject\Recur;
+
+use Exception;
+
+/**
+ * This exception gets thrown when a recurrence iterator produces 0 instances.
+ *
+ * This may happen when every occurence in a rrule is also in EXDATE.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ */
+class NoInstancesException extends Exception {
+
+}
diff --git a/vendor/sabre/vobject/lib/Recur/RDateIterator.php b/vendor/sabre/vobject/lib/Recur/RDateIterator.php
new file mode 100644
index 000000000..f44960e12
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Recur/RDateIterator.php
@@ -0,0 +1,182 @@
+<?php
+
+namespace Sabre\VObject\Recur;
+
+use DateTimeInterface;
+use Iterator;
+use Sabre\VObject\DateTimeParser;
+
+/**
+ * RRuleParser.
+ *
+ * This class receives an RRULE string, and allows you to iterate to get a list
+ * of dates in that recurrence.
+ *
+ * For instance, passing: FREQ=DAILY;LIMIT=5 will cause the iterator to contain
+ * 5 items, one for each day.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class RDateIterator implements Iterator {
+
+    /**
+     * Creates the Iterator.
+     *
+     * @param string|array $rrule
+     * @param DateTimeInterface $start
+     */
+    function __construct($rrule, DateTimeInterface $start) {
+
+        $this->startDate = $start;
+        $this->parseRDate($rrule);
+        $this->currentDate = clone $this->startDate;
+
+    }
+
+    /* Implementation of the Iterator interface {{{ */
+
+    function current() {
+
+        if (!$this->valid()) return;
+        return clone $this->currentDate;
+
+    }
+
+    /**
+     * Returns the current item number.
+     *
+     * @return int
+     */
+    function key() {
+
+        return $this->counter;
+
+    }
+
+    /**
+     * Returns whether the current item is a valid item for the recurrence
+     * iterator.
+     *
+     * @return bool
+     */
+    function valid() {
+
+        return ($this->counter <= count($this->dates));
+
+    }
+
+    /**
+     * Resets the iterator.
+     *
+     * @return void
+     */
+    function rewind() {
+
+        $this->currentDate = clone $this->startDate;
+        $this->counter = 0;
+
+    }
+
+    /**
+     * Goes on to the next iteration.
+     *
+     * @return void
+     */
+    function next() {
+
+        $this->counter++;
+        if (!$this->valid()) return;
+
+        $this->currentDate =
+            DateTimeParser::parse(
+                $this->dates[$this->counter - 1],
+                $this->startDate->getTimezone()
+            );
+
+    }
+
+    /* End of Iterator implementation }}} */
+
+    /**
+     * Returns true if this recurring event never ends.
+     *
+     * @return bool
+     */
+    function isInfinite() {
+
+        return false;
+
+    }
+
+    /**
+     * This method allows you to quickly go to the next occurrence after the
+     * specified date.
+     *
+     * @param DateTimeInterface $dt
+     *
+     * @return void
+     */
+    function fastForward(DateTimeInterface $dt) {
+
+        while ($this->valid() && $this->currentDate < $dt) {
+            $this->next();
+        }
+
+    }
+
+    /**
+     * The reference start date/time for the rrule.
+     *
+     * All calculations are based on this initial date.
+     *
+     * @var DateTimeInterface
+     */
+    protected $startDate;
+
+    /**
+     * The date of the current iteration. You can get this by calling
+     * ->current().
+     *
+     * @var DateTimeInterface
+     */
+    protected $currentDate;
+
+    /**
+     * The current item in the list.
+     *
+     * You can get this number with the key() method.
+     *
+     * @var int
+     */
+    protected $counter = 0;
+
+    /* }}} */
+
+    /**
+     * This method receives a string from an RRULE property, and populates this
+     * class with all the values.
+     *
+     * @param string|array $rrule
+     *
+     * @return void
+     */
+    protected function parseRDate($rdate) {
+
+        if (is_string($rdate)) {
+            $rdate = explode(',', $rdate);
+        }
+
+        $this->dates = $rdate;
+
+    }
+
+    /**
+     * Array with the RRULE dates
+     *
+     * @var array
+     */
+    protected $dates = [];
+
+}
diff --git a/vendor/sabre/vobject/lib/Recur/RRuleIterator.php b/vendor/sabre/vobject/lib/Recur/RRuleIterator.php
new file mode 100644
index 000000000..402e2de83
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Recur/RRuleIterator.php
@@ -0,0 +1,921 @@
+<?php
+
+namespace Sabre\VObject\Recur;
+
+use DateTimeInterface;
+use DateTimeImmutable;
+use Iterator;
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\InvalidDataException;
+use Sabre\VObject\Property;
+
+/**
+ * RRuleParser.
+ *
+ * This class receives an RRULE string, and allows you to iterate to get a list
+ * of dates in that recurrence.
+ *
+ * For instance, passing: FREQ=DAILY;LIMIT=5 will cause the iterator to contain
+ * 5 items, one for each day.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class RRuleIterator implements Iterator {
+
+    /**
+     * Creates the Iterator.
+     *
+     * @param string|array $rrule
+     * @param DateTimeInterface $start
+     */
+    function __construct($rrule, DateTimeInterface $start) {
+
+        $this->startDate = $start;
+        $this->parseRRule($rrule);
+        $this->currentDate = clone $this->startDate;
+
+    }
+
+    /* Implementation of the Iterator interface {{{ */
+
+    function current() {
+
+        if (!$this->valid()) return;
+        return clone $this->currentDate;
+
+    }
+
+    /**
+     * Returns the current item number.
+     *
+     * @return int
+     */
+    function key() {
+
+        return $this->counter;
+
+    }
+
+    /**
+     * Returns whether the current item is a valid item for the recurrence
+     * iterator. This will return false if we've gone beyond the UNTIL or COUNT
+     * statements.
+     *
+     * @return bool
+     */
+    function valid() {
+
+        if (!is_null($this->count)) {
+            return $this->counter < $this->count;
+        }
+        return is_null($this->until) || $this->currentDate <= $this->until;
+
+    }
+
+    /**
+     * Resets the iterator.
+     *
+     * @return void
+     */
+    function rewind() {
+
+        $this->currentDate = clone $this->startDate;
+        $this->counter = 0;
+
+    }
+
+    /**
+     * Goes on to the next iteration.
+     *
+     * @return void
+     */
+    function next() {
+
+        // Otherwise, we find the next event in the normal RRULE
+        // sequence.
+        switch ($this->frequency) {
+
+            case 'hourly' :
+                $this->nextHourly();
+                break;
+
+            case 'daily' :
+                $this->nextDaily();
+                break;
+
+            case 'weekly' :
+                $this->nextWeekly();
+                break;
+
+            case 'monthly' :
+                $this->nextMonthly();
+                break;
+
+            case 'yearly' :
+                $this->nextYearly();
+                break;
+
+        }
+        $this->counter++;
+
+    }
+
+    /* End of Iterator implementation }}} */
+
+    /**
+     * Returns true if this recurring event never ends.
+     *
+     * @return bool
+     */
+    function isInfinite() {
+
+        return !$this->count && !$this->until;
+
+    }
+
+    /**
+     * This method allows you to quickly go to the next occurrence after the
+     * specified date.
+     *
+     * @param DateTimeInterface $dt
+     *
+     * @return void
+     */
+    function fastForward(DateTimeInterface $dt) {
+
+        while ($this->valid() && $this->currentDate < $dt) {
+            $this->next();
+        }
+
+    }
+
+    /**
+     * The reference start date/time for the rrule.
+     *
+     * All calculations are based on this initial date.
+     *
+     * @var DateTimeInterface
+     */
+    protected $startDate;
+
+    /**
+     * The date of the current iteration. You can get this by calling
+     * ->current().
+     *
+     * @var DateTimeInterface
+     */
+    protected $currentDate;
+
+    /**
+     * Frequency is one of: secondly, minutely, hourly, daily, weekly, monthly,
+     * yearly.
+     *
+     * @var string
+     */
+    protected $frequency;
+
+    /**
+     * The number of recurrences, or 'null' if infinitely recurring.
+     *
+     * @var int
+     */
+    protected $count;
+
+    /**
+     * The interval.
+     *
+     * If for example frequency is set to daily, interval = 2 would mean every
+     * 2 days.
+     *
+     * @var int
+     */
+    protected $interval = 1;
+
+    /**
+     * The last instance of this recurrence, inclusively.
+     *
+     * @var DateTimeInterface|null
+     */
+    protected $until;
+
+    /**
+     * Which seconds to recur.
+     *
+     * This is an array of integers (between 0 and 60)
+     *
+     * @var array
+     */
+    protected $bySecond;
+
+    /**
+     * Which minutes to recur.
+     *
+     * This is an array of integers (between 0 and 59)
+     *
+     * @var array
+     */
+    protected $byMinute;
+
+    /**
+     * Which hours to recur.
+     *
+     * This is an array of integers (between 0 and 23)
+     *
+     * @var array
+     */
+    protected $byHour;
+
+    /**
+     * The current item in the list.
+     *
+     * You can get this number with the key() method.
+     *
+     * @var int
+     */
+    protected $counter = 0;
+
+    /**
+     * Which weekdays to recur.
+     *
+     * This is an array of weekdays
+     *
+     * This may also be preceeded by a positive or negative integer. If present,
+     * this indicates the nth occurrence of a specific day within the monthly or
+     * yearly rrule. For instance, -2TU indicates the second-last tuesday of
+     * the month, or year.
+     *
+     * @var array
+     */
+    protected $byDay;
+
+    /**
+     * Which days of the month to recur.
+     *
+     * This is an array of days of the months (1-31). The value can also be
+     * negative. -5 for instance means the 5th last day of the month.
+     *
+     * @var array
+     */
+    protected $byMonthDay;
+
+    /**
+     * Which days of the year to recur.
+     *
+     * This is an array with days of the year (1 to 366). The values can also
+     * be negative. For instance, -1 will always represent the last day of the
+     * year. (December 31st).
+     *
+     * @var array
+     */
+    protected $byYearDay;
+
+    /**
+     * Which week numbers to recur.
+     *
+     * This is an array of integers from 1 to 53. The values can also be
+     * negative. -1 will always refer to the last week of the year.
+     *
+     * @var array
+     */
+    protected $byWeekNo;
+
+    /**
+     * Which months to recur.
+     *
+     * This is an array of integers from 1 to 12.
+     *
+     * @var array
+     */
+    protected $byMonth;
+
+    /**
+     * Which items in an existing st to recur.
+     *
+     * These numbers work together with an existing by* rule. It specifies
+     * exactly which items of the existing by-rule to filter.
+     *
+     * Valid values are 1 to 366 and -1 to -366. As an example, this can be
+     * used to recur the last workday of the month.
+     *
+     * This would be done by setting frequency to 'monthly', byDay to
+     * 'MO,TU,WE,TH,FR' and bySetPos to -1.
+     *
+     * @var array
+     */
+    protected $bySetPos;
+
+    /**
+     * When the week starts.
+     *
+     * @var string
+     */
+    protected $weekStart = 'MO';
+
+    /* Functions that advance the iterator {{{ */
+
+    /**
+     * Does the processing for advancing the iterator for hourly frequency.
+     *
+     * @return void
+     */
+    protected function nextHourly() {
+
+        $this->currentDate = $this->currentDate->modify('+' . $this->interval . ' hours');
+
+    }
+
+    /**
+     * Does the processing for advancing the iterator for daily frequency.
+     *
+     * @return void
+     */
+    protected function nextDaily() {
+
+        if (!$this->byHour && !$this->byDay) {
+            $this->currentDate = $this->currentDate->modify('+' . $this->interval . ' days');
+            return;
+        }
+
+        if (!empty($this->byHour)) {
+            $recurrenceHours = $this->getHours();
+        }
+
+        if (!empty($this->byDay)) {
+            $recurrenceDays = $this->getDays();
+        }
+
+        if (!empty($this->byMonth)) {
+            $recurrenceMonths = $this->getMonths();
+        }
+
+        do {
+            if ($this->byHour) {
+                if ($this->currentDate->format('G') == '23') {
+                    // to obey the interval rule
+                    $this->currentDate = $this->currentDate->modify('+' . $this->interval - 1 . ' days');
+                }
+
+                $this->currentDate = $this->currentDate->modify('+1 hours');
+
+            } else {
+                $this->currentDate = $this->currentDate->modify('+' . $this->interval . ' days');
+
+            }
+
+            // Current month of the year
+            $currentMonth = $this->currentDate->format('n');
+
+            // Current day of the week
+            $currentDay = $this->currentDate->format('w');
+
+            // Current hour of the day
+            $currentHour = $this->currentDate->format('G');
+
+        } while (
+            ($this->byDay   && !in_array($currentDay, $recurrenceDays)) ||
+            ($this->byHour  && !in_array($currentHour, $recurrenceHours)) ||
+            ($this->byMonth && !in_array($currentMonth, $recurrenceMonths))
+        );
+
+    }
+
+    /**
+     * Does the processing for advancing the iterator for weekly frequency.
+     *
+     * @return void
+     */
+    protected function nextWeekly() {
+
+        if (!$this->byHour && !$this->byDay) {
+            $this->currentDate = $this->currentDate->modify('+' . $this->interval . ' weeks');
+            return;
+        }
+
+        if ($this->byHour) {
+            $recurrenceHours = $this->getHours();
+        }
+
+        if ($this->byDay) {
+            $recurrenceDays = $this->getDays();
+        }
+
+        // First day of the week:
+        $firstDay = $this->dayMap[$this->weekStart];
+
+        do {
+
+            if ($this->byHour) {
+                $this->currentDate = $this->currentDate->modify('+1 hours');
+            } else {
+                $this->currentDate = $this->currentDate->modify('+1 days');
+            }
+
+            // Current day of the week
+            $currentDay = (int)$this->currentDate->format('w');
+
+            // Current hour of the day
+            $currentHour = (int)$this->currentDate->format('G');
+
+            // We need to roll over to the next week
+            if ($currentDay === $firstDay && (!$this->byHour || $currentHour == '0')) {
+                $this->currentDate = $this->currentDate->modify('+' . $this->interval - 1 . ' weeks');
+
+                // We need to go to the first day of this week, but only if we
+                // are not already on this first day of this week.
+                if ($this->currentDate->format('w') != $firstDay) {
+                    $this->currentDate = $this->currentDate->modify('last ' . $this->dayNames[$this->dayMap[$this->weekStart]]);
+                }
+            }
+
+            // We have a match
+        } while (($this->byDay && !in_array($currentDay, $recurrenceDays)) || ($this->byHour && !in_array($currentHour, $recurrenceHours)));
+    }
+
+    /**
+     * Does the processing for advancing the iterator for monthly frequency.
+     *
+     * @return void
+     */
+    protected function nextMonthly() {
+
+        $currentDayOfMonth = $this->currentDate->format('j');
+        if (!$this->byMonthDay && !$this->byDay) {
+
+            // If the current day is higher than the 28th, rollover can
+            // occur to the next month. We Must skip these invalid
+            // entries.
+            if ($currentDayOfMonth < 29) {
+                $this->currentDate = $this->currentDate->modify('+' . $this->interval . ' months');
+            } else {
+                $increase = 0;
+                do {
+                    $increase++;
+                    $tempDate = clone $this->currentDate;
+                    $tempDate = $tempDate->modify('+ ' . ($this->interval * $increase) . ' months');
+                } while ($tempDate->format('j') != $currentDayOfMonth);
+                $this->currentDate = $tempDate;
+            }
+            return;
+        }
+
+        while (true) {
+
+            $occurrences = $this->getMonthlyOccurrences();
+
+            foreach ($occurrences as $occurrence) {
+
+                // The first occurrence thats higher than the current
+                // day of the month wins.
+                if ($occurrence > $currentDayOfMonth) {
+                    break 2;
+                }
+
+            }
+
+            // If we made it all the way here, it means there were no
+            // valid occurrences, and we need to advance to the next
+            // month.
+            //
+            // This line does not currently work in hhvm. Temporary workaround
+            // follows:
+            // $this->currentDate->modify('first day of this month');
+            $this->currentDate = new DateTimeImmutable($this->currentDate->format('Y-m-1 H:i:s'), $this->currentDate->getTimezone());
+            // end of workaround
+            $this->currentDate = $this->currentDate->modify('+ ' . $this->interval . ' months');
+
+            // This goes to 0 because we need to start counting at the
+            // beginning.
+            $currentDayOfMonth = 0;
+
+        }
+
+        $this->currentDate = $this->currentDate->setDate(
+            (int)$this->currentDate->format('Y'),
+            (int)$this->currentDate->format('n'),
+            (int)$occurrence
+        );
+
+    }
+
+    /**
+     * Does the processing for advancing the iterator for yearly frequency.
+     *
+     * @return void
+     */
+    protected function nextYearly() {
+
+        $currentMonth = $this->currentDate->format('n');
+        $currentYear = $this->currentDate->format('Y');
+        $currentDayOfMonth = $this->currentDate->format('j');
+
+        // No sub-rules, so we just advance by year
+        if (empty($this->byMonth)) {
+
+            // Unless it was a leap day!
+            if ($currentMonth == 2 && $currentDayOfMonth == 29) {
+
+                $counter = 0;
+                do {
+                    $counter++;
+                    // Here we increase the year count by the interval, until
+                    // we hit a date that's also in a leap year.
+                    //
+                    // We could just find the next interval that's dividable by
+                    // 4, but that would ignore the rule that there's no leap
+                    // year every year that's dividable by a 100, but not by
+                    // 400. (1800, 1900, 2100). So we just rely on the datetime
+                    // functions instead.
+                    $nextDate = clone $this->currentDate;
+                    $nextDate = $nextDate->modify('+ ' . ($this->interval * $counter) . ' years');
+                } while ($nextDate->format('n') != 2);
+
+                $this->currentDate = $nextDate;
+
+                return;
+
+            }
+
+            // The easiest form
+            $this->currentDate = $this->currentDate->modify('+' . $this->interval . ' years');
+            return;
+
+        }
+
+        $currentMonth = $this->currentDate->format('n');
+        $currentYear = $this->currentDate->format('Y');
+        $currentDayOfMonth = $this->currentDate->format('j');
+
+        $advancedToNewMonth = false;
+
+        // If we got a byDay or getMonthDay filter, we must first expand
+        // further.
+        if ($this->byDay || $this->byMonthDay) {
+
+            while (true) {
+
+                $occurrences = $this->getMonthlyOccurrences();
+
+                foreach ($occurrences as $occurrence) {
+
+                    // The first occurrence that's higher than the current
+                    // day of the month wins.
+                    // If we advanced to the next month or year, the first
+                    // occurrence is always correct.
+                    if ($occurrence > $currentDayOfMonth || $advancedToNewMonth) {
+                        break 2;
+                    }
+
+                }
+
+                // If we made it here, it means we need to advance to
+                // the next month or year.
+                $currentDayOfMonth = 1;
+                $advancedToNewMonth = true;
+                do {
+
+                    $currentMonth++;
+                    if ($currentMonth > 12) {
+                        $currentYear += $this->interval;
+                        $currentMonth = 1;
+                    }
+                } while (!in_array($currentMonth, $this->byMonth));
+
+                $this->currentDate = $this->currentDate->setDate(
+                    (int)$currentYear,
+                    (int)$currentMonth,
+                    (int)$currentDayOfMonth
+                );
+
+            }
+
+            // If we made it here, it means we got a valid occurrence
+            $this->currentDate = $this->currentDate->setDate(
+                (int)$currentYear,
+                (int)$currentMonth,
+                (int)$occurrence
+            );
+            return;
+
+        } else {
+
+            // These are the 'byMonth' rules, if there are no byDay or
+            // byMonthDay sub-rules.
+            do {
+
+                $currentMonth++;
+                if ($currentMonth > 12) {
+                    $currentYear += $this->interval;
+                    $currentMonth = 1;
+                }
+            } while (!in_array($currentMonth, $this->byMonth));
+            $this->currentDate = $this->currentDate->setDate(
+                (int)$currentYear,
+                (int)$currentMonth,
+                (int)$currentDayOfMonth
+            );
+
+            return;
+
+        }
+
+    }
+
+    /* }}} */
+
+    /**
+     * This method receives a string from an RRULE property, and populates this
+     * class with all the values.
+     *
+     * @param string|array $rrule
+     *
+     * @return void
+     */
+    protected function parseRRule($rrule) {
+
+        if (is_string($rrule)) {
+            $rrule = Property\ICalendar\Recur::stringToArray($rrule);
+        }
+
+        foreach ($rrule as $key => $value) {
+
+            $key = strtoupper($key);
+            switch ($key) {
+
+                case 'FREQ' :
+                    $value = strtolower($value);
+                    if (!in_array(
+                        $value,
+                        ['secondly', 'minutely', 'hourly', 'daily', 'weekly', 'monthly', 'yearly']
+                    )) {
+                        throw new InvalidDataException('Unknown value for FREQ=' . strtoupper($value));
+                    }
+                    $this->frequency = $value;
+                    break;
+
+                case 'UNTIL' :
+                    $this->until = DateTimeParser::parse($value, $this->startDate->getTimezone());
+
+                    // In some cases events are generated with an UNTIL=
+                    // parameter before the actual start of the event.
+                    //
+                    // Not sure why this is happening. We assume that the
+                    // intention was that the event only recurs once.
+                    //
+                    // So we are modifying the parameter so our code doesn't
+                    // break.
+                    if ($this->until < $this->startDate) {
+                        $this->until = $this->startDate;
+                    }
+                    break;
+
+                case 'INTERVAL' :
+                    // No break
+
+                case 'COUNT' :
+                    $val = (int)$value;
+                    if ($val < 1) {
+                        throw new InvalidDataException(strtoupper($key) . ' in RRULE must be a positive integer!');
+                    }
+                    $key = strtolower($key);
+                    $this->$key = $val;
+                    break;
+
+                case 'BYSECOND' :
+                    $this->bySecond = (array)$value;
+                    break;
+
+                case 'BYMINUTE' :
+                    $this->byMinute = (array)$value;
+                    break;
+
+                case 'BYHOUR' :
+                    $this->byHour = (array)$value;
+                    break;
+
+                case 'BYDAY' :
+                    $value = (array)$value;
+                    foreach ($value as $part) {
+                        if (!preg_match('#^  (-|\+)? ([1-5])? (MO|TU|WE|TH|FR|SA|SU) $# xi', $part)) {
+                            throw new InvalidDataException('Invalid part in BYDAY clause: ' . $part);
+                        }
+                    }
+                    $this->byDay = $value;
+                    break;
+
+                case 'BYMONTHDAY' :
+                    $this->byMonthDay = (array)$value;
+                    break;
+
+                case 'BYYEARDAY' :
+                    $this->byYearDay = (array)$value;
+                    break;
+
+                case 'BYWEEKNO' :
+                    $this->byWeekNo = (array)$value;
+                    break;
+
+                case 'BYMONTH' :
+                    $this->byMonth = (array)$value;
+                    break;
+
+                case 'BYSETPOS' :
+                    $this->bySetPos = (array)$value;
+                    break;
+
+                case 'WKST' :
+                    $this->weekStart = strtoupper($value);
+                    break;
+
+                default:
+                    throw new InvalidDataException('Not supported: ' . strtoupper($key));
+
+            }
+
+        }
+
+    }
+
+    /**
+     * Mappings between the day number and english day name.
+     *
+     * @var array
+     */
+    protected $dayNames = [
+        0 => 'Sunday',
+        1 => 'Monday',
+        2 => 'Tuesday',
+        3 => 'Wednesday',
+        4 => 'Thursday',
+        5 => 'Friday',
+        6 => 'Saturday',
+    ];
+
+    /**
+     * Returns all the occurrences for a monthly frequency with a 'byDay' or
+     * 'byMonthDay' expansion for the current month.
+     *
+     * The returned list is an array of integers with the day of month (1-31).
+     *
+     * @return array
+     */
+    protected function getMonthlyOccurrences() {
+
+        $startDate = clone $this->currentDate;
+
+        $byDayResults = [];
+
+        // Our strategy is to simply go through the byDays, advance the date to
+        // that point and add it to the results.
+        if ($this->byDay) foreach ($this->byDay as $day) {
+
+            $dayName = $this->dayNames[$this->dayMap[substr($day, -2)]];
+
+
+            // Dayname will be something like 'wednesday'. Now we need to find
+            // all wednesdays in this month.
+            $dayHits = [];
+
+            // workaround for missing 'first day of the month' support in hhvm
+            $checkDate = new \DateTime($startDate->format('Y-m-1'));
+            // workaround modify always advancing the date even if the current day is a $dayName in hhvm
+            if ($checkDate->format('l') !== $dayName) {
+                $checkDate = $checkDate->modify($dayName);
+            }
+
+            do {
+                $dayHits[] = $checkDate->format('j');
+                $checkDate = $checkDate->modify('next ' . $dayName);
+            } while ($checkDate->format('n') === $startDate->format('n'));
+
+            // So now we have 'all wednesdays' for month. It is however
+            // possible that the user only really wanted the 1st, 2nd or last
+            // wednesday.
+            if (strlen($day) > 2) {
+                $offset = (int)substr($day, 0, -2);
+
+                if ($offset > 0) {
+                    // It is possible that the day does not exist, such as a
+                    // 5th or 6th wednesday of the month.
+                    if (isset($dayHits[$offset - 1])) {
+                        $byDayResults[] = $dayHits[$offset - 1];
+                    }
+                } else {
+
+                    // if it was negative we count from the end of the array
+                    // might not exist, fx. -5th tuesday
+                    if (isset($dayHits[count($dayHits) + $offset])) {
+                        $byDayResults[] = $dayHits[count($dayHits) + $offset];
+                    }
+                }
+            } else {
+                // There was no counter (first, second, last wednesdays), so we
+                // just need to add the all to the list).
+                $byDayResults = array_merge($byDayResults, $dayHits);
+
+            }
+
+        }
+
+        $byMonthDayResults = [];
+        if ($this->byMonthDay) foreach ($this->byMonthDay as $monthDay) {
+
+            // Removing values that are out of range for this month
+            if ($monthDay > $startDate->format('t') ||
+                $monthDay < 0 - $startDate->format('t')) {
+                    continue;
+            }
+            if ($monthDay > 0) {
+                $byMonthDayResults[] = $monthDay;
+            } else {
+                // Negative values
+                $byMonthDayResults[] = $startDate->format('t') + 1 + $monthDay;
+            }
+        }
+
+        // If there was just byDay or just byMonthDay, they just specify our
+        // (almost) final list. If both were provided, then byDay limits the
+        // list.
+        if ($this->byMonthDay && $this->byDay) {
+            $result = array_intersect($byMonthDayResults, $byDayResults);
+        } elseif ($this->byMonthDay) {
+            $result = $byMonthDayResults;
+        } else {
+            $result = $byDayResults;
+        }
+        $result = array_unique($result);
+        sort($result, SORT_NUMERIC);
+
+        // The last thing that needs checking is the BYSETPOS. If it's set, it
+        // means only certain items in the set survive the filter.
+        if (!$this->bySetPos) {
+            return $result;
+        }
+
+        $filteredResult = [];
+        foreach ($this->bySetPos as $setPos) {
+
+            if ($setPos < 0) {
+                $setPos = count($result) + ($setPos + 1);
+            }
+            if (isset($result[$setPos - 1])) {
+                $filteredResult[] = $result[$setPos - 1];
+            }
+        }
+
+        sort($filteredResult, SORT_NUMERIC);
+        return $filteredResult;
+
+    }
+
+    /**
+     * Simple mapping from iCalendar day names to day numbers.
+     *
+     * @var array
+     */
+    protected $dayMap = [
+        'SU' => 0,
+        'MO' => 1,
+        'TU' => 2,
+        'WE' => 3,
+        'TH' => 4,
+        'FR' => 5,
+        'SA' => 6,
+    ];
+
+    protected function getHours() {
+
+        $recurrenceHours = [];
+        foreach ($this->byHour as $byHour) {
+            $recurrenceHours[] = $byHour;
+        }
+
+        return $recurrenceHours;
+    }
+
+    protected function getDays() {
+
+        $recurrenceDays = [];
+        foreach ($this->byDay as $byDay) {
+
+            // The day may be preceeded with a positive (+n) or
+            // negative (-n) integer. However, this does not make
+            // sense in 'weekly' so we ignore it here.
+            $recurrenceDays[] = $this->dayMap[substr($byDay, -2)];
+
+        }
+
+        return $recurrenceDays;
+    }
+
+    protected function getMonths() {
+
+        $recurrenceMonths = [];
+        foreach ($this->byMonth as $byMonth) {
+            $recurrenceMonths[] = $byMonth;
+        }
+
+        return $recurrenceMonths;
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component.php
deleted file mode 100644
index 1c1d92444..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component.php
+++ /dev/null
@@ -1,405 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * VObject Component
- *
- * This class represents a VCALENDAR/VCARD component. A component is for example
- * VEVENT, VTODO and also VCALENDAR. It starts with BEGIN:COMPONENTNAME and
- * ends with END:COMPONENTNAME
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class Component extends Node {
-
-    /**
-     * Name, for example VEVENT
-     *
-     * @var string
-     */
-    public $name;
-
-    /**
-     * Children properties and components
-     *
-     * @var array
-     */
-    public $children = array();
-
-    /**
-     * If components are added to this map, they will be automatically mapped
-     * to their respective classes, if parsed by the reader or constructed with
-     * the 'create' method.
-     *
-     * @var array
-     */
-    static public $classMap = array(
-        'VALARM'        => 'Sabre\\VObject\\Component\\VAlarm',
-        'VCALENDAR'     => 'Sabre\\VObject\\Component\\VCalendar',
-        'VCARD'         => 'Sabre\\VObject\\Component\\VCard',
-        'VEVENT'        => 'Sabre\\VObject\\Component\\VEvent',
-        'VJOURNAL'      => 'Sabre\\VObject\\Component\\VJournal',
-        'VTODO'         => 'Sabre\\VObject\\Component\\VTodo',
-        'VFREEBUSY'     => 'Sabre\\VObject\\Component\\VFreeBusy',
-    );
-
-    /**
-     * Creates the new component by name, but in addition will also see if
-     * there's a class mapped to the property name.
-     *
-     * @param string $name
-     * @param string $value
-     * @return Component
-     */
-    static public function create($name, $value = null) {
-
-        $name = strtoupper($name);
-
-        if (isset(self::$classMap[$name])) {
-            return new self::$classMap[$name]($name, $value);
-        } else {
-            return new self($name, $value);
-        }
-
-    }
-
-    /**
-     * Creates a new component.
-     *
-     * By default this object will iterate over its own children, but this can
-     * be overridden with the iterator argument
-     *
-     * @param string $name
-     * @param ElementList $iterator
-     */
-    public function __construct($name, ElementList $iterator = null) {
-
-        $this->name = strtoupper($name);
-        if (!is_null($iterator)) $this->iterator = $iterator;
-
-    }
-
-    /**
-     * Turns the object back into a serialized blob.
-     *
-     * @return string
-     */
-    public function serialize() {
-
-        $str = "BEGIN:" . $this->name . "\r\n";
-
-        /**
-         * Gives a component a 'score' for sorting purposes.
-         *
-         * This is solely used by the childrenSort method.
-         *
-         * A higher score means the item will be lower in the list.
-         * To avoid score collisions, each "score category" has a reasonable
-         * space to accomodate elements. The $key is added to the $score to
-         * preserve the original relative order of elements.
-         *
-         * @param int $key
-         * @param array $array
-         * @return int
-         */
-        $sortScore = function($key, $array) {
-
-            if ($array[$key] instanceof Component) {
-
-                // We want to encode VTIMEZONE first, this is a personal
-                // preference.
-                if ($array[$key]->name === 'VTIMEZONE') {
-                    $score=300000000;
-                    return $score+$key;
-                } else {
-                    $score=400000000;
-                    return $score+$key;
-                }
-            } else {
-                // Properties get encoded first
-                // VCARD version 4.0 wants the VERSION property to appear first
-                if ($array[$key] instanceof Property) {
-                    if ($array[$key]->name === 'VERSION') {
-                        $score=100000000;
-                        return $score+$key;
-                    } else {
-                        // All other properties
-                        $score=200000000;
-                        return $score+$key;
-                    }
-                }
-            }
-
-        };
-
-        $tmp = $this->children;
-        uksort($this->children, function($a, $b) use ($sortScore, $tmp) {
-
-            $sA = $sortScore($a, $tmp);
-            $sB = $sortScore($b, $tmp);
-
-            if ($sA === $sB) return 0;
-
-            return ($sA < $sB) ? -1 : 1;
-
-        });
-
-        foreach($this->children as $child) $str.=$child->serialize();
-        $str.= "END:" . $this->name . "\r\n";
-
-        return $str;
-
-    }
-
-    /**
-     * Adds a new component or element
-     *
-     * You can call this method with the following syntaxes:
-     *
-     * add(Node $node)
-     * add(string $name, $value, array $parameters = array())
-     *
-     * The first version adds an Element
-     * The second adds a property as a string.
-     *
-     * @param mixed $item
-     * @param mixed $itemValue
-     * @return void
-     */
-    public function add($item, $itemValue = null, array $parameters = array()) {
-
-        if ($item instanceof Node) {
-            if (!is_null($itemValue)) {
-                throw new \InvalidArgumentException('The second argument must not be specified, when passing a VObject Node');
-            }
-            $item->parent = $this;
-            $this->children[] = $item;
-        } elseif(is_string($item)) {
-
-            $item = Property::create($item,$itemValue, $parameters);
-            $item->parent = $this;
-            $this->children[] = $item;
-
-        } else {
-
-            throw new \InvalidArgumentException('The first argument must either be a \\Sabre\\VObject\\Node or a string');
-
-        }
-
-    }
-
-    /**
-     * Returns an iterable list of children
-     *
-     * @return ElementList
-     */
-    public function children() {
-
-        return new ElementList($this->children);
-
-    }
-
-    /**
-     * Returns an array with elements that match the specified name.
-     *
-     * This function is also aware of MIME-Directory groups (as they appear in
-     * vcards). This means that if a property is grouped as "HOME.EMAIL", it
-     * will also be returned when searching for just "EMAIL". If you want to
-     * search for a property in a specific group, you can select on the entire
-     * string ("HOME.EMAIL"). If you want to search on a specific property that
-     * has not been assigned a group, specify ".EMAIL".
-     *
-     * Keys are retained from the 'children' array, which may be confusing in
-     * certain cases.
-     *
-     * @param string $name
-     * @return array
-     */
-    public function select($name) {
-
-        $group = null;
-        $name = strtoupper($name);
-        if (strpos($name,'.')!==false) {
-            list($group,$name) = explode('.', $name, 2);
-        }
-
-        $result = array();
-        foreach($this->children as $key=>$child) {
-
-            if (
-                strtoupper($child->name) === $name &&
-                (is_null($group) || ( $child instanceof Property && strtoupper($child->group) === $group))
-            ) {
-
-                $result[$key] = $child;
-
-            }
-        }
-
-        reset($result);
-        return $result;
-
-    }
-
-    /**
-     * This method only returns a list of sub-components. Properties are
-     * ignored.
-     *
-     * @return array
-     */
-    public function getComponents() {
-
-        $result = array();
-        foreach($this->children as $child) {
-            if ($child instanceof Component) {
-                $result[] = $child;
-            }
-        }
-
-        return $result;
-
-    }
-
-    /**
-     * Validates the node for correctness.
-     *
-     * The following options are supported:
-     *   - Node::REPAIR - If something is broken, and automatic repair may
-     *                    be attempted.
-     *
-     * An array is returned with warnings.
-     *
-     * Every item in the array has the following properties:
-     *    * level - (number between 1 and 3 with severity information)
-     *    * message - (human readable message)
-     *    * node - (reference to the offending node)
-     *
-     * @param int $options
-     * @return array
-     */
-    public function validate($options = 0) {
-
-        $result = array();
-        foreach($this->children as $child) {
-            $result = array_merge($result, $child->validate($options));
-        }
-        return $result;
-
-    }
-
-    /* Magic property accessors {{{ */
-
-    /**
-     * Using 'get' you will either get a property or component,
-     *
-     * If there were no child-elements found with the specified name,
-     * null is returned.
-     *
-     * @param string $name
-     * @return Property
-     */
-    public function __get($name) {
-
-        $matches = $this->select($name);
-        if (count($matches)===0) {
-            return null;
-        } else {
-            $firstMatch = current($matches);
-            /** @var $firstMatch Property */
-            $firstMatch->setIterator(new ElementList(array_values($matches)));
-            return $firstMatch;
-        }
-
-    }
-
-    /**
-     * This method checks if a sub-element with the specified name exists.
-     *
-     * @param string $name
-     * @return bool
-     */
-    public function __isset($name) {
-
-        $matches = $this->select($name);
-        return count($matches)>0;
-
-    }
-
-    /**
-     * Using the setter method you can add properties or subcomponents
-     *
-     * You can either pass a Component, Property
-     * object, or a string to automatically create a Property.
-     *
-     * If the item already exists, it will be removed. If you want to add
-     * a new item with the same name, always use the add() method.
-     *
-     * @param string $name
-     * @param mixed $value
-     * @return void
-     */
-    public function __set($name, $value) {
-
-        $matches = $this->select($name);
-        $overWrite = count($matches)?key($matches):null;
-
-        if ($value instanceof Component || $value instanceof Property) {
-            $value->parent = $this;
-            if (!is_null($overWrite)) {
-                $this->children[$overWrite] = $value;
-            } else {
-                $this->children[] = $value;
-            }
-        } elseif (is_scalar($value)) {
-            $property = Property::create($name,$value);
-            $property->parent = $this;
-            if (!is_null($overWrite)) {
-                $this->children[$overWrite] = $property;
-            } else {
-                $this->children[] = $property;
-            }
-        } else {
-            throw new \InvalidArgumentException('You must pass a \\Sabre\\VObject\\Component, \\Sabre\\VObject\\Property or scalar type');
-        }
-
-    }
-
-    /**
-     * Removes all properties and components within this component.
-     *
-     * @param string $name
-     * @return void
-     */
-    public function __unset($name) {
-
-        $matches = $this->select($name);
-        foreach($matches as $k=>$child) {
-
-            unset($this->children[$k]);
-            $child->parent = null;
-
-        }
-
-    }
-
-    /* }}} */
-
-    /**
-     * This method is automatically called when the object is cloned.
-     * Specifically, this will ensure all child elements are also cloned.
-     *
-     * @return void
-     */
-    public function __clone() {
-
-        foreach($this->children as $key=>$child) {
-            $this->children[$key] = clone $child;
-            $this->children[$key]->parent = $this;
-        }
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VCalendar.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component/VCalendar.php
deleted file mode 100644
index 9de67982e..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VCalendar.php
+++ /dev/null
@@ -1,244 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Component;
-
-use Sabre\VObject;
-
-/**
- * The VCalendar component
- *
- * This component adds functionality to a component, specific for a VCALENDAR.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class VCalendar extends VObject\Document {
-
-    static $defaultName = 'VCALENDAR';
-
-    /**
-     * Returns a list of all 'base components'. For instance, if an Event has
-     * a recurrence rule, and one instance is overridden, the overridden event
-     * will have the same UID, but will be excluded from this list.
-     *
-     * VTIMEZONE components will always be excluded.
-     *
-     * @param string $componentName filter by component name
-     * @return array
-     */
-    public function getBaseComponents($componentName = null) {
-
-        $components = array();
-        foreach($this->children as $component) {
-
-            if (!$component instanceof VObject\Component)
-                continue;
-
-            if (isset($component->{'RECURRENCE-ID'}))
-                continue;
-
-            if ($componentName && $component->name !== strtoupper($componentName))
-                continue;
-
-            if ($component->name === 'VTIMEZONE')
-                continue;
-
-            $components[] = $component;
-
-        }
-
-        return $components;
-
-    }
-
-    /**
-     * If this calendar object, has events with recurrence rules, this method
-     * can be used to expand the event into multiple sub-events.
-     *
-     * Each event will be stripped from it's recurrence information, and only
-     * the instances of the event in the specified timerange will be left
-     * alone.
-     *
-     * In addition, this method will cause timezone information to be stripped,
-     * and normalized to UTC.
-     *
-     * This method will alter the VCalendar. This cannot be reversed.
-     *
-     * This functionality is specifically used by the CalDAV standard. It is
-     * possible for clients to request expand events, if they are rather simple
-     * clients and do not have the possibility to calculate recurrences.
-     *
-     * @param DateTime $start
-     * @param DateTime $end
-     * @return void
-     */
-    public function expand(\DateTime $start, \DateTime $end) {
-
-        $newEvents = array();
-
-        foreach($this->select('VEVENT') as $key=>$vevent) {
-
-            if (isset($vevent->{'RECURRENCE-ID'})) {
-                unset($this->children[$key]);
-                continue;
-            }
-
-
-            if (!$vevent->rrule) {
-                unset($this->children[$key]);
-                if ($vevent->isInTimeRange($start, $end)) {
-                    $newEvents[] = $vevent;
-                }
-                continue;
-            }
-
-            $uid = (string)$vevent->uid;
-            if (!$uid) {
-                throw new \LogicException('Event did not have a UID!');
-            }
-
-            $it = new VObject\RecurrenceIterator($this, $vevent->uid);
-            $it->fastForward($start);
-
-            while($it->valid() && $it->getDTStart() < $end) {
-
-                if ($it->getDTEnd() > $start) {
-
-                    $newEvents[] = $it->getEventObject();
-
-                }
-                $it->next();
-
-            }
-            unset($this->children[$key]);
-
-        }
-
-        foreach($newEvents as $newEvent) {
-
-            foreach($newEvent->children as $child) {
-                if ($child instanceof VObject\Property\DateTime &&
-                    $child->getDateType() == VObject\Property\DateTime::LOCALTZ) {
-                        $child->setDateTime($child->getDateTime(),VObject\Property\DateTime::UTC);
-                    }
-            }
-
-            $this->add($newEvent);
-
-        }
-
-        // Removing all VTIMEZONE components
-        unset($this->VTIMEZONE);
-
-    }
-
-    /**
-     * Validates the node for correctness.
-     * An array is returned with warnings.
-     *
-     * Every item in the array has the following properties:
-     *    * level - (number between 1 and 3 with severity information)
-     *    * message - (human readable message)
-     *    * node - (reference to the offending node)
-     *
-     * @return array
-     */
-    /*
-    public function validate() {
-
-        $warnings = array();
-
-        $version = $this->select('VERSION');
-        if (count($version)!==1) {
-            $warnings[] = array(
-                'level' => 1,
-                'message' => 'The VERSION property must appear in the VCALENDAR component exactly 1 time',
-                'node' => $this,
-            );
-        } else {
-            if ((string)$this->VERSION !== '2.0') {
-                $warnings[] = array(
-                    'level' => 1,
-                    'message' => 'Only iCalendar version 2.0 as defined in rfc5545 is supported.',
-                    'node' => $this,
-                );
-            }
-        }
-        $version = $this->select('PRODID');
-        if (count($version)!==1) {
-            $warnings[] = array(
-                'level' => 2,
-                'message' => 'The PRODID property must appear in the VCALENDAR component exactly 1 time',
-                'node' => $this,
-            );
-        }
-        if (count($this->CALSCALE) > 1) {
-            $warnings[] = array(
-                'level' => 2,
-                'message' => 'The CALSCALE property must not be specified more than once.',
-                'node' => $this,
-            );
-        }
-        if (count($this->METHOD) > 1) {
-            $warnings[] = array(
-                'level' => 2,
-                'message' => 'The METHOD property must not be specified more than once.',
-                'node' => $this,
-            );
-        }
-
-        $allowedComponents = array(
-            'VEVENT',
-            'VTODO',
-            'VJOURNAL',
-            'VFREEBUSY',
-            'VTIMEZONE',
-        );
-        $allowedProperties = array(
-            'PRODID',
-            'VERSION',
-            'CALSCALE',
-            'METHOD',
-        );
-        $componentsFound = 0;
-        foreach($this->children as $child) {
-            if($child instanceof Component) {
-                $componentsFound++;
-                if (!in_array($child->name, $allowedComponents)) {
-                    $warnings[] = array(
-                        'level' => 1,
-                        'message' => 'The ' . $child->name . " component is not allowed in the VCALENDAR component",
-                        'node' => $this,
-                    );
-                }
-            }
-            if ($child instanceof Property) {
-                if (!in_array($child->name, $allowedProperties)) {
-                    $warnings[] = array(
-                        'level' => 2,
-                        'message' => 'The ' . $child->name . " property is not allowed in the VCALENDAR component",
-                        'node' => $this,
-                    );
-                }
-            }
-        }
-
-        if ($componentsFound===0) {
-            $warnings[] = array(
-                'level' => 1,
-                'message' => 'An iCalendar object must have at least 1 component.',
-                'node' => $this,
-            );
-        }
-
-        return array_merge(
-            $warnings,
-            parent::validate()
-        );
-
-    }
-     */
-
-}
-
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VCard.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component/VCard.php
deleted file mode 100644
index 0fc8b7020..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VCard.php
+++ /dev/null
@@ -1,107 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Component;
-
-use Sabre\VObject;
-
-/**
- * The VCard component
- *
- * This component represents the BEGIN:VCARD and END:VCARD found in every
- * vcard.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class VCard extends VObject\Component {
-
-    static $defaultName = 'VCARD';
-
-    /**
-     * VCards with version 2.1, 3.0 and 4.0 are found.
-     *
-     * If the VCARD doesn't know its version, 4.0 is assumed.
-     */
-    const DEFAULT_VERSION = '4.0';
-
-    /**
-     * Validates the node for correctness.
-     *
-     * The following options are supported:
-     *   - Node::REPAIR - If something is broken, and automatic repair may
-     *                    be attempted.
-     *
-     * An array is returned with warnings.
-     *
-     * Every item in the array has the following properties:
-     *    * level - (number between 1 and 3 with severity information)
-     *    * message - (human readable message)
-     *    * node - (reference to the offending node)
-     *
-     * @param int $options
-     * @return array
-     */
-    public function validate($options = 0) {
-
-        $warnings = array();
-
-        $version = $this->select('VERSION');
-        if (count($version)!==1) {
-            $warnings[] = array(
-                'level' => 1,
-                'message' => 'The VERSION property must appear in the VCARD component exactly 1 time',
-                'node' => $this,
-            );
-            if ($options & self::REPAIR) {
-                $this->VERSION = self::DEFAULT_VERSION;
-            }
-        } else {
-            $version = (string)$this->VERSION;
-            if ($version!=='2.1' && $version!=='3.0' && $version!=='4.0') {
-                $warnings[] = array(
-                    'level' => 1,
-                    'message' => 'Only vcard version 4.0 (RFC6350), version 3.0 (RFC2426) or version 2.1 (icm-vcard-2.1) are supported.',
-                    'node' => $this,
-                );
-                if ($options & self::REPAIR) {
-                    $this->VERSION = '4.0';
-                }
-            }
-
-        }
-        $fn = $this->select('FN');
-        if (count($fn)!==1) {
-            $warnings[] = array(
-                'level' => 1,
-                'message' => 'The FN property must appear in the VCARD component exactly 1 time',
-                'node' => $this,
-            );
-            if (($options & self::REPAIR) && count($fn) === 0) {
-                // We're going to try to see if we can use the contents of the
-                // N property.
-                if (isset($this->N)) {
-                    $value = explode(';', (string)$this->N);
-                    if (isset($value[1]) && $value[1]) {
-                        $this->FN = $value[1] . ' ' . $value[0];
-                    } else {
-                        $this->FN = $value[0];
-                    }
-
-                // Otherwise, the ORG property may work
-                } elseif (isset($this->ORG)) {
-                    $this->FN = (string)$this->ORG;
-                }
-
-            }
-        }
-
-        return array_merge(
-            parent::validate($options),
-            $warnings
-        );
-
-    }
-
-}
-
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VEvent.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component/VEvent.php
deleted file mode 100644
index 2375c5317..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VEvent.php
+++ /dev/null
@@ -1,70 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Component;
-use Sabre\VObject;
-
-/**
- * VEvent component
- *
- * This component contains some additional functionality specific for VEVENT's.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class VEvent extends VObject\Component {
-
-    /**
-     * Returns true or false depending on if the event falls in the specified
-     * time-range. This is used for filtering purposes.
-     *
-     * The rules used to determine if an event falls within the specified
-     * time-range is based on the CalDAV specification.
-     *
-     * @param \DateTime $start
-     * @param \DateTime $end
-     * @return bool
-     */
-    public function isInTimeRange(\DateTime $start, \DateTime $end) {
-
-        if ($this->RRULE) {
-            $it = new VObject\RecurrenceIterator($this);
-            $it->fastForward($start);
-
-            // We fast-forwarded to a spot where the end-time of the
-            // recurrence instance exceeded the start of the requested
-            // time-range.
-            //
-            // If the starttime of the recurrence did not exceed the
-            // end of the time range as well, we have a match.
-            return ($it->getDTStart() < $end && $it->getDTEnd() > $start);
-
-        }
-
-        $effectiveStart = $this->DTSTART->getDateTime();
-        if (isset($this->DTEND)) {
-
-            // The DTEND property is considered non inclusive. So for a 3 day
-            // event in july, dtstart and dtend would have to be July 1st and
-            // July 4th respectively.
-            //
-            // See:
-            // http://tools.ietf.org/html/rfc5545#page-54
-            $effectiveEnd = $this->DTEND->getDateTime();
-
-        } elseif (isset($this->DURATION)) {
-            $effectiveEnd = clone $effectiveStart;
-            $effectiveEnd->add( VObject\DateTimeParser::parseDuration($this->DURATION) );
-        } elseif ($this->DTSTART->getDateType() == VObject\Property\DateTime::DATE) {
-            $effectiveEnd = clone $effectiveStart;
-            $effectiveEnd->modify('+1 day');
-        } else {
-            $effectiveEnd = clone $effectiveStart;
-        }
-        return (
-            ($start <= $effectiveEnd) && ($end > $effectiveStart)
-        );
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VFreeBusy.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component/VFreeBusy.php
deleted file mode 100644
index 7afe9fdb3..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VFreeBusy.php
+++ /dev/null
@@ -1,68 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Component;
-
-use Sabre\VObject;
-
-/**
- * The VFreeBusy component
- *
- * This component adds functionality to a component, specific for VFREEBUSY
- * components.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class VFreeBusy extends VObject\Component {
-
-    /**
-     * Checks based on the contained FREEBUSY information, if a timeslot is
-     * available.
-     *
-     * @param DateTime $start
-     * @param Datetime $end
-     * @return bool
-     */
-    public function isFree(\DateTime $start, \Datetime $end) {
-
-        foreach($this->select('FREEBUSY') as $freebusy) {
-
-            // We are only interested in FBTYPE=BUSY (the default),
-            // FBTYPE=BUSY-TENTATIVE or FBTYPE=BUSY-UNAVAILABLE.
-            if (isset($freebusy['FBTYPE']) && strtoupper(substr((string)$freebusy['FBTYPE'],0,4))!=='BUSY') {
-                continue;
-            }
-
-            // The freebusy component can hold more than 1 value, separated by
-            // commas.
-            $periods = explode(',', (string)$freebusy);
-
-            foreach($periods as $period) {
-                // Every period is formatted as [start]/[end]. The start is an
-                // absolute UTC time, the end may be an absolute UTC time, or
-                // duration (relative) value.
-                list($busyStart, $busyEnd) = explode('/', $period);
-
-                $busyStart = VObject\DateTimeParser::parse($busyStart);
-                $busyEnd = VObject\DateTimeParser::parse($busyEnd);
-                if ($busyEnd instanceof \DateInterval) {
-                    $tmp = clone $busyStart;
-                    $tmp->add($busyEnd);
-                    $busyEnd = $tmp;
-                }
-
-                if($start < $busyEnd && $end > $busyStart) {
-                    return false;
-                }
-
-            }
-
-        }
-
-        return true;
-
-    }
-
-}
-
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VJournal.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component/VJournal.php
deleted file mode 100644
index 232887879..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VJournal.php
+++ /dev/null
@@ -1,46 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Component;
-
-use Sabre\VObject;
-
-/**
- * VJournal component
- *
- * This component contains some additional functionality specific for VJOURNALs.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class VJournal extends VObject\Component {
-
-    /**
-     * Returns true or false depending on if the event falls in the specified
-     * time-range. This is used for filtering purposes.
-     *
-     * The rules used to determine if an event falls within the specified
-     * time-range is based on the CalDAV specification.
-     *
-     * @param DateTime $start
-     * @param DateTime $end
-     * @return bool
-     */
-    public function isInTimeRange(\DateTime $start, \DateTime $end) {
-
-        $dtstart = isset($this->DTSTART)?$this->DTSTART->getDateTime():null;
-        if ($dtstart) {
-            $effectiveEnd = clone $dtstart;
-            if ($this->DTSTART->getDateType() == VObject\Property\DateTime::DATE) {
-                $effectiveEnd->modify('+1 day');
-            }
-
-            return ($start <= $effectiveEnd && $end > $dtstart);
-
-        }
-        return false;
-
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VTodo.php b/vendor/sabre/vobject/lib/Sabre/VObject/Component/VTodo.php
deleted file mode 100644
index b1579cf74..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Component/VTodo.php
+++ /dev/null
@@ -1,68 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Component;
-
-use Sabre\VObject;
-
-/**
- * VTodo component
- *
- * This component contains some additional functionality specific for VTODOs.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class VTodo extends VObject\Component {
-
-    /**
-     * Returns true or false depending on if the event falls in the specified
-     * time-range. This is used for filtering purposes.
-     *
-     * The rules used to determine if an event falls within the specified
-     * time-range is based on the CalDAV specification.
-     *
-     * @param DateTime $start
-     * @param DateTime $end
-     * @return bool
-     */
-    public function isInTimeRange(\DateTime $start, \DateTime $end) {
-
-        $dtstart = isset($this->DTSTART)?$this->DTSTART->getDateTime():null;
-        $duration = isset($this->DURATION)?VObject\DateTimeParser::parseDuration($this->DURATION):null;
-        $due = isset($this->DUE)?$this->DUE->getDateTime():null;
-        $completed = isset($this->COMPLETED)?$this->COMPLETED->getDateTime():null;
-        $created = isset($this->CREATED)?$this->CREATED->getDateTime():null;
-
-        if ($dtstart) {
-            if ($duration) {
-                $effectiveEnd = clone $dtstart;
-                $effectiveEnd->add($duration);
-                return $start <= $effectiveEnd && $end > $dtstart;
-            } elseif ($due) {
-                return
-                    ($start < $due || $start <= $dtstart) &&
-                    ($end > $dtstart || $end >= $due);
-            } else {
-                return $start <= $dtstart && $end > $dtstart;
-            }
-        }
-        if ($due) {
-            return ($start < $due && $end >= $due);
-        }
-        if ($completed && $created) {
-            return
-                ($start <= $created || $start <= $completed) &&
-                ($end >= $created || $end >= $completed);
-        }
-        if ($completed) {
-            return ($start <= $completed && $end >= $completed);
-        }
-        if ($created) {
-            return ($end > $created);
-        }
-        return true;
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/DateTimeParser.php b/vendor/sabre/vobject/lib/Sabre/VObject/DateTimeParser.php
deleted file mode 100644
index 03600506d..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/DateTimeParser.php
+++ /dev/null
@@ -1,181 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * DateTimeParser
- *
- * This class is responsible for parsing the several different date and time
- * formats iCalendar and vCards have.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class DateTimeParser {
-
-    /**
-     * Parses an iCalendar (rfc5545) formatted datetime and returns a DateTime object
-     *
-     * Specifying a reference timezone is optional. It will only be used
-     * if the non-UTC format is used. The argument is used as a reference, the
-     * returned DateTime object will still be in the UTC timezone.
-     *
-     * @param string $dt
-     * @param DateTimeZone $tz
-     * @return DateTime
-     */
-    static public function parseDateTime($dt,\DateTimeZone $tz = null) {
-
-        // Format is YYYYMMDD + "T" + hhmmss
-        $result = preg_match('/^([1-4][0-9]{3})([0-1][0-9])([0-3][0-9])T([0-2][0-9])([0-5][0-9])([0-5][0-9])([Z]?)$/',$dt,$matches);
-
-        if (!$result) {
-            throw new \LogicException('The supplied iCalendar datetime value is incorrect: ' . $dt);
-        }
-
-        if ($matches[7]==='Z' || is_null($tz)) {
-            $tz = new \DateTimeZone('UTC');
-        }
-        $date = new \DateTime($matches[1] . '-' . $matches[2] . '-' . $matches[3] . ' ' . $matches[4] . ':' . $matches[5] .':' . $matches[6], $tz);
-
-        // Still resetting the timezone, to normalize everything to UTC
-        $date->setTimeZone(new \DateTimeZone('UTC'));
-        return $date;
-
-    }
-
-    /**
-     * Parses an iCalendar (rfc5545) formatted date and returns a DateTime object
-     *
-     * @param string $date
-     * @return DateTime
-     */
-    static public function parseDate($date) {
-
-        // Format is YYYYMMDD
-        $result = preg_match('/^([1-4][0-9]{3})([0-1][0-9])([0-3][0-9])$/',$date,$matches);
-
-        if (!$result) {
-            throw new \LogicException('The supplied iCalendar date value is incorrect: ' . $date);
-        }
-
-        $date = new \DateTime($matches[1] . '-' . $matches[2] . '-' . $matches[3], new \DateTimeZone('UTC'));
-        return $date;
-
-    }
-
-    /**
-     * Parses an iCalendar (RFC5545) formatted duration value.
-     *
-     * This method will either return a DateTimeInterval object, or a string
-     * suitable for strtotime or DateTime::modify.
-     *
-     * @param string $duration
-     * @param bool $asString
-     * @return DateInterval|string
-     */
-    static public function parseDuration($duration, $asString = false) {
-
-        $result = preg_match('/^(?P<plusminus>\+|-)?P((?P<week>\d+)W)?((?P<day>\d+)D)?(T((?P<hour>\d+)H)?((?P<minute>\d+)M)?((?P<second>\d+)S)?)?$/', $duration, $matches);
-        if (!$result) {
-            throw new \LogicException('The supplied iCalendar duration value is incorrect: ' . $duration);
-        }
-
-        if (!$asString) {
-            $invert = false;
-            if ($matches['plusminus']==='-') {
-                $invert = true;
-            }
-
-
-            $parts = array(
-                'week',
-                'day',
-                'hour',
-                'minute',
-                'second',
-            );
-            foreach($parts as $part) {
-                $matches[$part] = isset($matches[$part])&&$matches[$part]?(int)$matches[$part]:0;
-            }
-
-
-            // We need to re-construct the $duration string, because weeks and
-            // days are not supported by DateInterval in the same string.
-            $duration = 'P';
-            $days = $matches['day'];
-            if ($matches['week']) {
-                $days+=$matches['week']*7;
-            }
-            if ($days)
-                $duration.=$days . 'D';
-
-            if ($matches['minute'] || $matches['second'] || $matches['hour']) {
-                $duration.='T';
-
-                if ($matches['hour'])
-                    $duration.=$matches['hour'].'H';
-
-                if ($matches['minute'])
-                    $duration.=$matches['minute'].'M';
-
-                if ($matches['second'])
-                    $duration.=$matches['second'].'S';
-
-            }
-
-            if ($duration==='P') {
-                $duration = 'PT0S';
-            }
-            $iv = new \DateInterval($duration);
-            if ($invert) $iv->invert = true;
-
-            return $iv;
-
-        }
-
-
-
-        $parts = array(
-            'week',
-            'day',
-            'hour',
-            'minute',
-            'second',
-        );
-
-        $newDur = '';
-        foreach($parts as $part) {
-            if (isset($matches[$part]) && $matches[$part]) {
-                $newDur.=' '.$matches[$part] . ' ' . $part . 's';
-            }
-        }
-
-        $newDur = ($matches['plusminus']==='-'?'-':'+') . trim($newDur);
-        if ($newDur === '+') { $newDur = '+0 seconds'; };
-        return $newDur;
-
-    }
-
-    /**
-     * Parses either a Date or DateTime, or Duration value.
-     *
-     * @param string $date
-     * @param DateTimeZone|string $referenceTZ
-     * @return DateTime|DateInterval
-     */
-    static public function parse($date, $referenceTZ = null) {
-
-        if ($date[0]==='P' || ($date[0]==='-' && $date[1]==='P')) {
-            return self::parseDuration($date);
-        } elseif (strlen($date)===8) {
-            return self::parseDate($date);
-        } else {
-            return self::parseDateTime($date, $referenceTZ);
-        }
-
-    }
-
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Document.php b/vendor/sabre/vobject/lib/Sabre/VObject/Document.php
deleted file mode 100644
index 50a662ee9..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Document.php
+++ /dev/null
@@ -1,109 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * Document
- *
- * A document is just like a component, except that it's also the top level
- * element.
- *
- * Both a VCALENDAR and a VCARD are considered documents.
- *
- * This class also provides a registry for document types.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH. All rights reserved.
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-abstract class Document extends Component {
-
-    /**
-     * The default name for this component.
-     *
-     * This should be 'VCALENDAR' or 'VCARD'.
-     *
-     * @var string
-     */
-    static $defaultName;
-
-    /**
-     * Creates a new document.
-     *
-     * We're changing the default behavior slightly here. First, we don't want
-     * to have to specify a name (we already know it), and we want to allow
-     * children to be specified in the first argument.
-     *
-     * But, the default behavior also works.
-     *
-     * So the two sigs:
-     *
-     * new Document(array $children = array());
-     * new Document(string $name, array $children = array())
-     *
-     * @return void
-     */
-    public function __construct() {
-
-        $args = func_get_args();
-        if (count($args)===0 || is_array($args[0])) {
-            array_unshift($args, static::$defaultName);
-            call_user_func_array(array('parent', '__construct'), $args);
-        } else {
-            call_user_func_array(array('parent', '__construct'), $args);
-        }
-
-    }
-
-    /**
-     * Creates a new component
-     *
-     * This method automatically searches for the correct component class, based
-     * on its name.
-     *
-     * You can specify the children either in key=>value syntax, in which case
-     * properties will automatically be created, or you can just pass a list of
-     * Component and Property object.
-     *
-     * @param string $name
-     * @param array $children
-     * @return Component
-     */
-    public function createComponent($name, array $children = array()) {
-
-        $component = Component::create($name);
-        foreach($children as $k=>$v) {
-
-            if ($v instanceof Node) {
-                $component->add($v);
-            } else {
-                $component->add($k, $v);
-            }
-
-        }
-        return $component;
-
-    }
-
-    /**
-     * Factory method for creating new properties
-     *
-     * This method automatically searches for the correct property class, based
-     * on its name.
-     *
-     * You can specify the parameters either in key=>value syntax, in which case
-     * parameters will automatically be created, or you can just pass a list of
-     * Parameter objects.
-     *
-     * @param string $name
-     * @param mixed $value
-     * @param array $parameters
-     * @return Property
-     */
-    public function createProperty($name, $value = null, array $parameters = array()) {
-
-        return Property::create($name, $value, $parameters);
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/ElementList.php b/vendor/sabre/vobject/lib/Sabre/VObject/ElementList.php
deleted file mode 100644
index 1c203708e..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/ElementList.php
+++ /dev/null
@@ -1,172 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * VObject ElementList
- *
- * This class represents a list of elements. Lists are the result of queries,
- * such as doing $vcalendar->vevent where there's multiple VEVENT objects.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class ElementList implements \Iterator, \Countable, \ArrayAccess {
-
-    /**
-     * Inner elements
-     *
-     * @var array
-     */
-    protected $elements = array();
-
-    /**
-     * Creates the element list.
-     *
-     * @param array $elements
-     */
-    public function __construct(array $elements) {
-
-        $this->elements = $elements;
-
-    }
-
-    /* {{{ Iterator interface */
-
-    /**
-     * Current position
-     *
-     * @var int
-     */
-    private $key = 0;
-
-    /**
-     * Returns current item in iteration
-     *
-     * @return Element
-     */
-    public function current() {
-
-        return $this->elements[$this->key];
-
-    }
-
-    /**
-     * To the next item in the iterator
-     *
-     * @return void
-     */
-    public function next() {
-
-        $this->key++;
-
-    }
-
-    /**
-     * Returns the current iterator key
-     *
-     * @return int
-     */
-    public function key() {
-
-        return $this->key;
-
-    }
-
-    /**
-     * Returns true if the current position in the iterator is a valid one
-     *
-     * @return bool
-     */
-    public function valid() {
-
-        return isset($this->elements[$this->key]);
-
-    }
-
-    /**
-     * Rewinds the iterator
-     *
-     * @return void
-     */
-    public function rewind() {
-
-        $this->key = 0;
-
-    }
-
-    /* }}} */
-
-    /* {{{ Countable interface */
-
-    /**
-     * Returns the number of elements
-     *
-     * @return int
-     */
-    public function count() {
-
-        return count($this->elements);
-
-    }
-
-    /* }}} */
-
-    /* {{{ ArrayAccess Interface */
-
-
-    /**
-     * Checks if an item exists through ArrayAccess.
-     *
-     * @param int $offset
-     * @return bool
-     */
-    public function offsetExists($offset) {
-
-        return isset($this->elements[$offset]);
-
-    }
-
-    /**
-     * Gets an item through ArrayAccess.
-     *
-     * @param int $offset
-     * @return mixed
-     */
-    public function offsetGet($offset) {
-
-        return $this->elements[$offset];
-
-    }
-
-    /**
-     * Sets an item through ArrayAccess.
-     *
-     * @param int $offset
-     * @param mixed $value
-     * @return void
-     */
-    public function offsetSet($offset,$value) {
-
-        throw new \LogicException('You can not add new objects to an ElementList');
-
-    }
-
-    /**
-     * Sets an item through ArrayAccess.
-     *
-     * This method just forwards the request to the inner iterator
-     *
-     * @param int $offset
-     * @return void
-     */
-    public function offsetUnset($offset) {
-
-        throw new \LogicException('You can not remove objects from an ElementList');
-
-    }
-
-    /* }}} */
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/FreeBusyGenerator.php b/vendor/sabre/vobject/lib/Sabre/VObject/FreeBusyGenerator.php
deleted file mode 100644
index 96d0be5ac..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/FreeBusyGenerator.php
+++ /dev/null
@@ -1,322 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * This class helps with generating FREEBUSY reports based on existing sets of
- * objects.
- *
- * It only looks at VEVENT and VFREEBUSY objects from the sourcedata, and
- * generates a single VFREEBUSY object.
- *
- * VFREEBUSY components are described in RFC5545, The rules for what should
- * go in a single freebusy report is taken from RFC4791, section 7.10.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class FreeBusyGenerator {
-
-    /**
-     * Input objects
-     *
-     * @var array
-     */
-    protected $objects;
-
-    /**
-     * Start of range
-     *
-     * @var DateTime|null
-     */
-    protected $start;
-
-    /**
-     * End of range
-     *
-     * @var DateTime|null
-     */
-    protected $end;
-
-    /**
-     * VCALENDAR object
-     *
-     * @var Component
-     */
-    protected $baseObject;
-
-    /**
-     * Creates the generator.
-     *
-     * Check the setTimeRange and setObjects methods for details about the
-     * arguments.
-     *
-     * @param DateTime $start
-     * @param DateTime $end
-     * @param mixed $objects
-     * @return void
-     */
-    public function __construct(\DateTime $start = null, \DateTime $end = null, $objects = null) {
-
-        if ($start && $end) {
-            $this->setTimeRange($start, $end);
-        }
-
-        if ($objects) {
-            $this->setObjects($objects);
-        }
-
-    }
-
-    /**
-     * Sets the VCALENDAR object.
-     *
-     * If this is set, it will not be generated for you. You are responsible
-     * for setting things like the METHOD, CALSCALE, VERSION, etc..
-     *
-     * The VFREEBUSY object will be automatically added though.
-     *
-     * @param Component $vcalendar
-     * @return void
-     */
-    public function setBaseObject(Component $vcalendar) {
-
-        $this->baseObject = $vcalendar;
-
-    }
-
-    /**
-     * Sets the input objects
-     *
-     * You must either specify a valendar object as a strong, or as the parse
-     * Component.
-     * It's also possible to specify multiple objects as an array.
-     *
-     * @param mixed $objects
-     * @return void
-     */
-    public function setObjects($objects) {
-
-        if (!is_array($objects)) {
-            $objects = array($objects);
-        }
-
-        $this->objects = array();
-        foreach($objects as $object) {
-
-            if (is_string($object)) {
-                $this->objects[] = Reader::read($object);
-            } elseif ($object instanceof Component) {
-                $this->objects[] = $object;
-            } else {
-                throw new \InvalidArgumentException('You can only pass strings or \\Sabre\\VObject\\Component arguments to setObjects');
-            }
-
-        }
-
-    }
-
-    /**
-     * Sets the time range
-     *
-     * Any freebusy object falling outside of this time range will be ignored.
-     *
-     * @param DateTime $start
-     * @param DateTime $end
-     * @return void
-     */
-    public function setTimeRange(\DateTime $start = null, \DateTime $end = null) {
-
-        $this->start = $start;
-        $this->end = $end;
-
-    }
-
-    /**
-     * Parses the input data and returns a correct VFREEBUSY object, wrapped in
-     * a VCALENDAR.
-     *
-     * @return Component
-     */
-    public function getResult() {
-
-        $busyTimes = array();
-
-        foreach($this->objects as $object) {
-
-            foreach($object->getBaseComponents() as $component) {
-
-                switch($component->name) {
-
-                    case 'VEVENT' :
-
-                        $FBTYPE = 'BUSY';
-                        if (isset($component->TRANSP) && (strtoupper($component->TRANSP) === 'TRANSPARENT')) {
-                            break;
-                        }
-                        if (isset($component->STATUS)) {
-                            $status = strtoupper($component->STATUS);
-                            if ($status==='CANCELLED') {
-                                break;
-                            }
-                            if ($status==='TENTATIVE') {
-                                $FBTYPE = 'BUSY-TENTATIVE';
-                            }
-                        }
-
-                        $times = array();
-
-                        if ($component->RRULE) {
-
-                            $iterator = new RecurrenceIterator($object, (string)$component->uid);
-                            if ($this->start) {
-                                $iterator->fastForward($this->start);
-                            }
-
-                            $maxRecurrences = 200;
-
-                            while($iterator->valid() && --$maxRecurrences) {
-
-                                $startTime = $iterator->getDTStart();
-                                if ($this->end && $startTime > $this->end) {
-                                    break;
-                                }
-                                $times[] = array(
-                                    $iterator->getDTStart(),
-                                    $iterator->getDTEnd(),
-                                );
-
-                                $iterator->next();
-
-                            }
-
-                        } else {
-
-                            $startTime = $component->DTSTART->getDateTime();
-                            if ($this->end && $startTime > $this->end) {
-                                break;
-                            }
-                            $endTime = null;
-                            if (isset($component->DTEND)) {
-                                $endTime = $component->DTEND->getDateTime();
-                            } elseif (isset($component->DURATION)) {
-                                $duration = DateTimeParser::parseDuration((string)$component->DURATION);
-                                $endTime = clone $startTime;
-                                $endTime->add($duration);
-                            } elseif ($component->DTSTART->getDateType() === Property\DateTime::DATE) {
-                                $endTime = clone $startTime;
-                                $endTime->modify('+1 day');
-                            } else {
-                                // The event had no duration (0 seconds)
-                                break;
-                            }
-
-                            $times[] = array($startTime, $endTime);
-
-                        }
-
-                        foreach($times as $time) {
-
-                            if ($this->end && $time[0] > $this->end) break;
-                            if ($this->start && $time[1] < $this->start) break;
-
-                            $busyTimes[] = array(
-                                $time[0],
-                                $time[1],
-                                $FBTYPE,
-                            );
-                        }
-                        break;
-
-                    case 'VFREEBUSY' :
-                        foreach($component->FREEBUSY as $freebusy) {
-
-                            $fbType = isset($freebusy['FBTYPE'])?strtoupper($freebusy['FBTYPE']):'BUSY';
-
-                            // Skipping intervals marked as 'free'
-                            if ($fbType==='FREE')
-                                continue;
-
-                            $values = explode(',', $freebusy);
-                            foreach($values as $value) {
-                                list($startTime, $endTime) = explode('/', $value);
-                                $startTime = DateTimeParser::parseDateTime($startTime);
-
-                                if (substr($endTime,0,1)==='P' || substr($endTime,0,2)==='-P') {
-                                    $duration = DateTimeParser::parseDuration($endTime);
-                                    $endTime = clone $startTime;
-                                    $endTime->add($duration);
-                                } else {
-                                    $endTime = DateTimeParser::parseDateTime($endTime);
-                                }
-
-                                if($this->start && $this->start > $endTime) continue;
-                                if($this->end && $this->end < $startTime) continue;
-                                $busyTimes[] = array(
-                                    $startTime,
-                                    $endTime,
-                                    $fbType
-                                );
-
-                            }
-
-
-                        }
-                        break;
-
-
-
-                }
-
-
-            }
-
-        }
-
-        if ($this->baseObject) {
-            $calendar = $this->baseObject;
-        } else {
-            $calendar = Component::create('VCALENDAR');
-            $calendar->version = '2.0';
-            $calendar->prodid = '-//Sabre//Sabre VObject ' . Version::VERSION . '//EN';
-            $calendar->calscale = 'GREGORIAN';
-        }
-
-        $vfreebusy = Component::create('VFREEBUSY');
-        $calendar->add($vfreebusy);
-
-        if ($this->start) {
-            $dtstart = Property::create('DTSTART');
-            $dtstart->setDateTime($this->start,Property\DateTime::UTC);
-            $vfreebusy->add($dtstart);
-        }
-        if ($this->end) {
-            $dtend = Property::create('DTEND');
-            $dtend->setDateTime($this->end,Property\DateTime::UTC);
-            $vfreebusy->add($dtend);
-        }
-        $dtstamp = Property::create('DTSTAMP');
-        $dtstamp->setDateTime(new \DateTime('now'), Property\DateTime::UTC);
-        $vfreebusy->add($dtstamp);
-
-        foreach($busyTimes as $busyTime) {
-
-            $busyTime[0]->setTimeZone(new \DateTimeZone('UTC'));
-            $busyTime[1]->setTimeZone(new \DateTimeZone('UTC'));
-
-            $prop = Property::create(
-                'FREEBUSY',
-                $busyTime[0]->format('Ymd\\THis\\Z') . '/' . $busyTime[1]->format('Ymd\\THis\\Z')
-            );
-            $prop['FBTYPE'] = $busyTime[2];
-            $vfreebusy->add($prop);
-
-        }
-
-        return $calendar;
-
-    }
-
-}
-
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Node.php b/vendor/sabre/vobject/lib/Sabre/VObject/Node.php
deleted file mode 100644
index bee68ec2a..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Node.php
+++ /dev/null
@@ -1,187 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * Base class for all nodes
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-abstract class Node implements \IteratorAggregate, \ArrayAccess, \Countable {
-
-    /**
-     * The following constants are used by the validate() method.
-     */
-    const REPAIR = 1;
-
-    /**
-     * Turns the object back into a serialized blob.
-     *
-     * @return string
-     */
-    abstract function serialize();
-
-    /**
-     * Iterator override
-     *
-     * @var ElementList
-     */
-    protected $iterator = null;
-
-    /**
-     * A link to the parent node
-     *
-     * @var Node
-     */
-    public $parent = null;
-
-    /**
-     * Validates the node for correctness.
-     *
-     * The following options are supported:
-     *   - Node::REPAIR - If something is broken, and automatic repair may
-     *                    be attempted.
-     *
-     * An array is returned with warnings.
-     *
-     * Every item in the array has the following properties:
-     *    * level - (number between 1 and 3 with severity information)
-     *    * message - (human readable message)
-     *    * node - (reference to the offending node)
-     *
-     * @param int $options
-     * @return array
-     */
-    public function validate($options = 0) {
-
-        return array();
-
-    }
-
-    /* {{{ IteratorAggregator interface */
-
-    /**
-     * Returns the iterator for this object
-     *
-     * @return ElementList
-     */
-    public function getIterator() {
-
-        if (!is_null($this->iterator))
-            return $this->iterator;
-
-        return new ElementList(array($this));
-
-    }
-
-    /**
-     * Sets the overridden iterator
-     *
-     * Note that this is not actually part of the iterator interface
-     *
-     * @param ElementList $iterator
-     * @return void
-     */
-    public function setIterator(ElementList $iterator) {
-
-        $this->iterator = $iterator;
-
-    }
-
-    /* }}} */
-
-    /* {{{ Countable interface */
-
-    /**
-     * Returns the number of elements
-     *
-     * @return int
-     */
-    public function count() {
-
-        $it = $this->getIterator();
-        return $it->count();
-
-    }
-
-    /* }}} */
-
-    /* {{{ ArrayAccess Interface */
-
-
-    /**
-     * Checks if an item exists through ArrayAccess.
-     *
-     * This method just forwards the request to the inner iterator
-     *
-     * @param int $offset
-     * @return bool
-     */
-    public function offsetExists($offset) {
-
-        $iterator = $this->getIterator();
-        return $iterator->offsetExists($offset);
-
-    }
-
-    /**
-     * Gets an item through ArrayAccess.
-     *
-     * This method just forwards the request to the inner iterator
-     *
-     * @param int $offset
-     * @return mixed
-     */
-    public function offsetGet($offset) {
-
-        $iterator = $this->getIterator();
-        return $iterator->offsetGet($offset);
-
-    }
-
-    /**
-     * Sets an item through ArrayAccess.
-     *
-     * This method just forwards the request to the inner iterator
-     *
-     * @param int $offset
-     * @param mixed $value
-     * @return void
-     */
-    public function offsetSet($offset,$value) {
-
-        $iterator = $this->getIterator();
-        $iterator->offsetSet($offset,$value);
-
-    // @codeCoverageIgnoreStart
-    //
-    // This method always throws an exception, so we ignore the closing
-    // brace
-    }
-    // @codeCoverageIgnoreEnd
-
-    /**
-     * Sets an item through ArrayAccess.
-     *
-     * This method just forwards the request to the inner iterator
-     *
-     * @param int $offset
-     * @return void
-     */
-    public function offsetUnset($offset) {
-
-        $iterator = $this->getIterator();
-        $iterator->offsetUnset($offset);
-
-    // @codeCoverageIgnoreStart
-    //
-    // This method always throws an exception, so we ignore the closing
-    // brace
-    }
-    // @codeCoverageIgnoreEnd
-
-    /* }}} */
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Parameter.php b/vendor/sabre/vobject/lib/Sabre/VObject/Parameter.php
deleted file mode 100644
index 72bf03b47..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Parameter.php
+++ /dev/null
@@ -1,104 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * VObject Parameter
- *
- * This class represents a parameter. A parameter is always tied to a property.
- * In the case of:
- *   DTSTART;VALUE=DATE:20101108
- * VALUE=DATE would be the parameter name and value.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class Parameter extends Node {
-
-    /**
-     * Parameter name
-     *
-     * @var string
-     */
-    public $name;
-
-    /**
-     * Parameter value
-     *
-     * @var string
-     */
-    public $value;
-
-    /**
-     * Sets up the object
-     *
-     * @param string $name
-     * @param string $value
-     */
-    public function __construct($name, $value = null) {
-
-        if (!is_scalar($value) && !is_null($value)) {
-            throw new \InvalidArgumentException('The value argument must be a scalar value or null');
-        }
-
-        $this->name = strtoupper($name);
-        $this->value = $value;
-
-    }
-
-    /**
-     * Returns the parameter's internal value.
-     *
-     * @return string
-     */
-    public function getValue() {
-
-        return $this->value;
-
-    }
-
-
-    /**
-     * Turns the object back into a serialized blob.
-     *
-     * @return string
-     */
-    public function serialize() {
-
-        if (is_null($this->value)) {
-            return $this->name;
-        }
-        $src = array(
-            '\\',
-            "\n",
-            ';',
-            ',',
-        );
-        $out = array(
-            '\\\\',
-            '\n',
-            '\;',
-            '\,',
-        );
-
-        $value = str_replace($src, $out, $this->value);
-        if (strpos($value,":")!==false) {
-            $value = '"' . $value . '"';
-        }
-        return $this->name . '=' . $value;
-
-    }
-
-    /**
-     * Called when this object is being cast to a string
-     *
-     * @return string
-     */
-    public function __toString() {
-
-        return $this->value;
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/ParseException.php b/vendor/sabre/vobject/lib/Sabre/VObject/ParseException.php
deleted file mode 100644
index 66b49c606..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/ParseException.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * Exception thrown by Reader if an invalid object was attempted to be parsed.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class ParseException extends \Exception { }
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Property.php b/vendor/sabre/vobject/lib/Sabre/VObject/Property.php
deleted file mode 100644
index 63ae64574..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Property.php
+++ /dev/null
@@ -1,444 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * VObject Property
- *
- * A property in VObject is usually in the form PARAMNAME:paramValue.
- * An example is : SUMMARY:Weekly meeting
- *
- * Properties can also have parameters:
- * SUMMARY;LANG=en:Weekly meeting.
- *
- * Parameters can be accessed using the ArrayAccess interface.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class Property extends Node {
-
-    /**
-     * Propertyname
-     *
-     * @var string
-     */
-    public $name;
-
-    /**
-     * Group name
-     *
-     * This may be something like 'HOME' for vcards.
-     *
-     * @var string
-     */
-    public $group;
-
-    /**
-     * Property parameters
-     *
-     * @var array
-     */
-    public $parameters = array();
-
-    /**
-     * Property value
-     *
-     * @var string
-     */
-    public $value;
-
-    /**
-     * If properties are added to this map, they will be automatically mapped
-     * to their respective classes, if parsed by the reader or constructed with
-     * the 'create' method.
-     *
-     * @var array
-     */
-    static public $classMap = array(
-        'COMPLETED'     => 'Sabre\\VObject\\Property\\DateTime',
-        'CREATED'       => 'Sabre\\VObject\\Property\\DateTime',
-        'DTEND'         => 'Sabre\\VObject\\Property\\DateTime',
-        'DTSTAMP'       => 'Sabre\\VObject\\Property\\DateTime',
-        'DTSTART'       => 'Sabre\\VObject\\Property\\DateTime',
-        'DUE'           => 'Sabre\\VObject\\Property\\DateTime',
-        'EXDATE'        => 'Sabre\\VObject\\Property\\MultiDateTime',
-        'LAST-MODIFIED' => 'Sabre\\VObject\\Property\\DateTime',
-        'RECURRENCE-ID' => 'Sabre\\VObject\\Property\\DateTime',
-        'TRIGGER'       => 'Sabre\\VObject\\Property\\DateTime',
-        'N'             => 'Sabre\\VObject\\Property\\Compound',
-        'ORG'           => 'Sabre\\VObject\\Property\\Compound',
-        'ADR'           => 'Sabre\\VObject\\Property\\Compound',
-        'CATEGORIES'    => 'Sabre\\VObject\\Property\\Compound',
-    );
-
-    /**
-     * Creates the new property by name, but in addition will also see if
-     * there's a class mapped to the property name.
-     *
-     * Parameters can be specified with the optional third argument. Parameters
-     * must be a key->value map of the parameter name, and value. If the value
-     * is specified as an array, it is assumed that multiple parameters with
-     * the same name should be added.
-     *
-     * @param string $name
-     * @param string $value
-     * @param array $parameters
-     * @return Property
-     */
-    static public function create($name, $value = null, array $parameters = array()) {
-
-        $name = strtoupper($name);
-        $shortName = $name;
-        $group = null;
-        if (strpos($shortName,'.')!==false) {
-            list($group, $shortName) = explode('.', $shortName);
-        }
-
-        if (isset(self::$classMap[$shortName])) {
-            return new self::$classMap[$shortName]($name, $value, $parameters);
-        } else {
-            return new self($name, $value, $parameters);
-        }
-
-    }
-
-    /**
-     * Creates a new property object
-     *
-     * Parameters can be specified with the optional third argument. Parameters
-     * must be a key->value map of the parameter name, and value. If the value
-     * is specified as an array, it is assumed that multiple parameters with
-     * the same name should be added.
-     *
-     * @param string $name
-     * @param string $value
-     * @param array $parameters
-     */
-    public function __construct($name, $value = null, array $parameters = array()) {
-
-        if (!is_scalar($value) && !is_null($value)) {
-            throw new \InvalidArgumentException('The value argument must be scalar or null');
-        }
-
-        $name = strtoupper($name);
-        $group = null;
-        if (strpos($name,'.')!==false) {
-            list($group, $name) = explode('.', $name);
-        }
-        $this->name = $name;
-        $this->group = $group;
-        $this->setValue($value);
-
-        foreach($parameters as $paramName => $paramValues) {
-
-            if (!is_array($paramValues)) {
-                $paramValues = array($paramValues);
-            }
-
-            foreach($paramValues as $paramValue) {
-                $this->add($paramName, $paramValue);
-            }
-
-        }
-
-    }
-
-    /**
-     * Updates the internal value
-     *
-     * @param string $value
-     * @return void
-     */
-    public function setValue($value) {
-
-        $this->value = $value;
-
-    }
-
-    /**
-     * Returns the internal value
-     *
-     * @param string $value
-     * @return string
-     */
-    public function getValue() {
-
-        return $this->value;
-
-    }
-
-    /**
-     * Turns the object back into a serialized blob.
-     *
-     * @return string
-     */
-    public function serialize() {
-
-        $str = $this->name;
-        if ($this->group) $str = $this->group . '.' . $this->name;
-
-        foreach($this->parameters as $param) {
-
-            $str.=';' . $param->serialize();
-
-        }
-
-        $src = array(
-            '\\',
-            "\n",
-            "\r",
-        );
-        $out = array(
-            '\\\\',
-            '\n',
-            '',
-        );
-        $str.=':' . str_replace($src, $out, $this->value);
-
-        $out = '';
-        while(strlen($str)>0) {
-            if (strlen($str)>75) {
-                $out.= mb_strcut($str,0,75,'utf-8') . "\r\n";
-                $str = ' ' . mb_strcut($str,75,strlen($str),'utf-8');
-            } else {
-                $out.=$str . "\r\n";
-                $str='';
-                break;
-            }
-        }
-
-        return $out;
-
-    }
-
-    /**
-     * Adds a new componenten or element
-     *
-     * You can call this method with the following syntaxes:
-     *
-     * add(Parameter $element)
-     * add(string $name, $value)
-     *
-     * The first version adds an Parameter
-     * The second adds a property as a string.
-     *
-     * @param mixed $item
-     * @param mixed $itemValue
-     * @return void
-     */
-    public function add($item, $itemValue = null) {
-
-        if ($item instanceof Parameter) {
-            if (!is_null($itemValue)) {
-                throw new \InvalidArgumentException('The second argument must not be specified, when passing a VObject');
-            }
-            $item->parent = $this;
-            $this->parameters[] = $item;
-        } elseif(is_string($item)) {
-
-            $parameter = new Parameter($item,$itemValue);
-            $parameter->parent = $this;
-            $this->parameters[] = $parameter;
-
-        } else {
-
-            throw new \InvalidArgumentException('The first argument must either be a Node a string');
-
-        }
-
-    }
-
-    /* ArrayAccess interface {{{ */
-
-    /**
-     * Checks if an array element exists
-     *
-     * @param mixed $name
-     * @return bool
-     */
-    public function offsetExists($name) {
-
-        if (is_int($name)) return parent::offsetExists($name);
-
-        $name = strtoupper($name);
-
-        foreach($this->parameters as $parameter) {
-            if ($parameter->name == $name) return true;
-        }
-        return false;
-
-    }
-
-    /**
-     * Returns a parameter, or parameter list.
-     *
-     * @param string $name
-     * @return Node
-     */
-    public function offsetGet($name) {
-
-        if (is_int($name)) return parent::offsetGet($name);
-        $name = strtoupper($name);
-
-        $result = array();
-        foreach($this->parameters as $parameter) {
-            if ($parameter->name == $name)
-                $result[] = $parameter;
-        }
-
-        if (count($result)===0) {
-            return null;
-        } elseif (count($result)===1) {
-            return $result[0];
-        } else {
-            $result[0]->setIterator(new ElementList($result));
-            return $result[0];
-        }
-
-    }
-
-    /**
-     * Creates a new parameter
-     *
-     * @param string $name
-     * @param mixed $value
-     * @return void
-     */
-    public function offsetSet($name, $value) {
-
-        if (is_int($name)) parent::offsetSet($name, $value);
-
-        if (is_scalar($value)) {
-            if (!is_string($name))
-                throw new \InvalidArgumentException('A parameter name must be specified. This means you cannot use the $array[]="string" to add parameters.');
-
-            $this->offsetUnset($name);
-            $parameter = new Parameter($name, $value);
-            $parameter->parent = $this;
-            $this->parameters[] = $parameter;
-
-        } elseif ($value instanceof Parameter) {
-            if (!is_null($name))
-                throw new \InvalidArgumentException('Don\'t specify a parameter name if you\'re passing a \\Sabre\\VObject\\Parameter. Add using $array[]=$parameterObject.');
-
-            $value->parent = $this;
-            $this->parameters[] = $value;
-        } else {
-            throw new \InvalidArgumentException('You can only add parameters to the property object');
-        }
-
-    }
-
-    /**
-     * Removes one or more parameters with the specified name
-     *
-     * @param string $name
-     * @return void
-     */
-    public function offsetUnset($name) {
-
-        if (is_int($name)) parent::offsetUnset($name);
-        $name = strtoupper($name);
-
-        foreach($this->parameters as $key=>$parameter) {
-            if ($parameter->name == $name) {
-                $parameter->parent = null;
-                unset($this->parameters[$key]);
-            }
-
-        }
-
-    }
-
-    /* }}} */
-
-    /**
-     * Called when this object is being cast to a string
-     *
-     * @return string
-     */
-    public function __toString() {
-
-        return (string)$this->value;
-
-    }
-
-    /**
-     * This method is automatically called when the object is cloned.
-     * Specifically, this will ensure all child elements are also cloned.
-     *
-     * @return void
-     */
-    public function __clone() {
-
-        foreach($this->parameters as $key=>$child) {
-            $this->parameters[$key] = clone $child;
-            $this->parameters[$key]->parent = $this;
-        }
-
-    }
-
-    /**
-     * Validates the node for correctness.
-     *
-     * The following options are supported:
-     *   - Node::REPAIR - If something is broken, and automatic repair may
-     *                    be attempted.
-     *
-     * An array is returned with warnings.
-     *
-     * Every item in the array has the following properties:
-     *    * level - (number between 1 and 3 with severity information)
-     *    * message - (human readable message)
-     *    * node - (reference to the offending node)
-     *
-     * @param int $options
-     * @return array
-     */
-    public function validate($options = 0) {
-
-        $warnings = array();
-
-        // Checking if our value is UTF-8
-        if (!StringUtil::isUTF8($this->value)) {
-            $warnings[] = array(
-                'level' => 1,
-                'message' => 'Property is not valid UTF-8!',
-                'node' => $this,
-            );
-            if ($options & self::REPAIR) {
-                $this->value = StringUtil::convertToUTF8($this->value);
-            }
-        }
-
-        // Checking if the propertyname does not contain any invalid bytes.
-        if (!preg_match('/^([A-Z0-9-]+)$/', $this->name)) {
-            $warnings[] = array(
-                'level' => 1,
-                'message' => 'The propertyname: ' . $this->name . ' contains invalid characters. Only A-Z, 0-9 and - are allowed',
-                'node' => $this,
-            );
-            if ($options & self::REPAIR) {
-                // Uppercasing and converting underscores to dashes.
-                $this->name = strtoupper(
-                    str_replace('_', '-', $this->name)
-                );
-                // Removing every other invalid character
-                $this->name = preg_replace('/([^A-Z0-9-])/u', '', $this->name);
-
-            }
-
-        }
-
-        // Validating inner parameters
-        foreach($this->parameters as $param) {
-            $warnings = array_merge($warnings, $param->validate($options));
-        }
-
-        return $warnings;
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Property/Compound.php b/vendor/sabre/vobject/lib/Sabre/VObject/Property/Compound.php
deleted file mode 100644
index 26f090069..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Property/Compound.php
+++ /dev/null
@@ -1,125 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Property;
-
-use Sabre\VObject;
-
-/**
- * Compound property.
- *
- * This class adds (de)serialization of compound properties to/from arrays.
- *
- * Currently the following properties from RFC 6350 are mapped to use this
- * class:
- *
- *  N:          Section 6.2.2
- *  ADR:        Section 6.3.1
- *  ORG:        Section 6.6.4
- *  CATEGORIES: Section 6.7.1
- *
- * In order to use this correctly, you must call setParts and getParts to
- * retrieve and modify dates respectively.
- *
- * @author Thomas Tanghus (http://tanghus.net/)
- * @author Lars Kneschke
- * @author Evert Pot (http://evertpot.com/)
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class Compound extends VObject\Property {
-
-    /**
-     * If property names are added to this map, they will be (de)serialised as arrays
-     * using the getParts() and setParts() methods.
-     * The keys are the property names, values are delimiter chars.
-     *
-     * @var array
-     */
-    static public $delimiterMap = array(
-        'N'           =>    ';',
-        'ADR'         =>    ';',
-        'ORG'         =>    ';',
-        'CATEGORIES'  =>    ',',
-    );
-
-    /**
-     * The currently used delimiter.
-     *
-     * @var string
-     */
-    protected $delimiter = null;
-
-    /**
-     * Get a compound value as an array.
-     *
-     * @param $name string
-     * @return array
-     */
-    public function getParts() {
-
-        if (is_null($this->value)) {
-            return array();
-        }
-
-        $delimiter = $this->getDelimiter();
-
-        // split by any $delimiter which is NOT prefixed by a slash.
-        // Note that this is not a a perfect solution. If a value is prefixed
-        // by two slashes, it should actually be split anyway.
-        //
-        // Hopefully we can fix this better in a future version, where we can
-        // break compatibility a bit.
-        $compoundValues = preg_split("/(?<!\\\)$delimiter/", $this->value);
-
-        // remove slashes from any semicolon and comma left escaped in the single values
-        $compoundValues = array_map(
-            function($val) {
-                return strtr($val, array('\,' => ',', '\;' => ';'));
-        }, $compoundValues);
-
-        return $compoundValues;
-
-    }
-
-    /**
-     * Returns the delimiter for this property.
-     *
-     * @return string
-     */
-    public function getDelimiter() {
-
-        if (!$this->delimiter) {
-            if (isset(self::$delimiterMap[$this->name])) {
-                $this->delimiter = self::$delimiterMap[$this->name];
-            } else {
-                // To be a bit future proof, we are going to default the
-                // delimiter to ;
-                $this->delimiter = ';';
-            }
-        }
-        return $this->delimiter;
-
-    }
-
-    /**
-     * Set a compound value as an array.
-     *
-     *
-     * @param $name string
-     * @return array
-     */
-    public function setParts(array $values) {
-
-        // add slashes to all semicolons and commas in the single values
-        $values = array_map(
-            function($val) {
-                return strtr($val, array(',' => '\,', ';' => '\;'));
-            }, $values);
-
-        $this->setValue(
-            implode($this->getDelimiter(), $values)
-        );
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Property/DateTime.php b/vendor/sabre/vobject/lib/Sabre/VObject/Property/DateTime.php
deleted file mode 100644
index 95e9b0209..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Property/DateTime.php
+++ /dev/null
@@ -1,245 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Property;
-
-use Sabre\VObject;
-
-/**
- * DateTime property
- *
- * This element is used for iCalendar properties such as the DTSTART property.
- * It basically provides a few helper functions that make it easier to deal
- * with these. It supports both DATE-TIME and DATE values.
- *
- * In order to use this correctly, you must call setDateTime and getDateTime to
- * retrieve and modify dates respectively.
- *
- * If you use the 'value' or properties directly, this object does not keep
- * reference and results might appear incorrectly.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class DateTime extends VObject\Property {
-
-    /**
-     * Local 'floating' time
-     */
-    const LOCAL = 1;
-
-    /**
-     * UTC-based time
-     */
-    const UTC = 2;
-
-    /**
-     * Local time plus timezone
-     */
-    const LOCALTZ = 3;
-
-    /**
-     * Only a date, time is ignored
-     */
-    const DATE = 4;
-
-    /**
-     * DateTime representation
-     *
-     * @var \DateTime
-     */
-    protected $dateTime;
-
-    /**
-     * dateType
-     *
-     * @var int
-     */
-    protected $dateType;
-
-    /**
-     * Updates the Date and Time.
-     *
-     * @param \DateTime $dt
-     * @param int $dateType
-     * @return void
-     */
-    public function setDateTime(\DateTime $dt, $dateType = self::LOCALTZ) {
-
-        switch($dateType) {
-
-            case self::LOCAL :
-                $this->setValue($dt->format('Ymd\\THis'));
-                $this->offsetUnset('VALUE');
-                $this->offsetUnset('TZID');
-                $this->offsetSet('VALUE','DATE-TIME');
-                break;
-            case self::UTC :
-                $dt->setTimeZone(new \DateTimeZone('UTC'));
-                $this->setValue($dt->format('Ymd\\THis\\Z'));
-                $this->offsetUnset('VALUE');
-                $this->offsetUnset('TZID');
-                $this->offsetSet('VALUE','DATE-TIME');
-                break;
-            case self::LOCALTZ :
-                $this->setValue($dt->format('Ymd\\THis'));
-                $this->offsetUnset('VALUE');
-                $this->offsetUnset('TZID');
-                $this->offsetSet('VALUE','DATE-TIME');
-                $this->offsetSet('TZID', $dt->getTimeZone()->getName());
-                break;
-            case self::DATE :
-                $this->setValue($dt->format('Ymd'));
-                $this->offsetUnset('VALUE');
-                $this->offsetUnset('TZID');
-                $this->offsetSet('VALUE','DATE');
-                break;
-            default :
-                throw new \InvalidArgumentException('You must pass a valid dateType constant');
-
-        }
-        $this->dateTime = $dt;
-        $this->dateType = $dateType;
-
-    }
-
-    /**
-     * Returns the current DateTime value.
-     *
-     * If no value was set, this method returns null.
-     *
-     * @return \DateTime|null
-     */
-    public function getDateTime() {
-
-        if ($this->dateTime)
-            return $this->dateTime;
-
-        list(
-            $this->dateType,
-            $this->dateTime
-        ) = self::parseData($this->value, $this);
-        return $this->dateTime;
-
-    }
-
-    /**
-     * Returns the type of Date format.
-     *
-     * This method returns one of the format constants. If no date was set,
-     * this method will return null.
-     *
-     * @return int|null
-     */
-    public function getDateType() {
-
-        if ($this->dateType)
-            return $this->dateType;
-
-        list(
-            $this->dateType,
-            $this->dateTime,
-        ) = self::parseData($this->value, $this);
-        return $this->dateType;
-
-    }
-
-    /**
-     * This method will return true, if the property had a date and a time, as
-     * opposed to only a date.
-     *
-     * @return bool
-     */
-    public function hasTime() {
-
-        return $this->getDateType()!==self::DATE;
-
-    }
-
-    /**
-     * Parses the internal data structure to figure out what the current date
-     * and time is.
-     *
-     * The returned array contains two elements:
-     *   1. A 'DateType' constant (as defined on this class), or null.
-     *   2. A DateTime object (or null)
-     *
-     * @param string|null $propertyValue The string to parse (yymmdd or
-     *                                   ymmddThhmmss, etc..)
-     * @param \Sabre\VObject\Property|null $property The instance of the
-     *                                              property we're parsing.
-     * @return array
-     */
-    static public function parseData($propertyValue, VObject\Property $property = null) {
-
-        if (is_null($propertyValue)) {
-            return array(null, null);
-        }
-
-        $date = '(?P<year>[1-2][0-9]{3})(?P<month>[0-1][0-9])(?P<date>[0-3][0-9])';
-        $time = '(?P<hour>[0-2][0-9])(?P<minute>[0-5][0-9])(?P<second>[0-5][0-9])';
-        $regex = "/^$date(T$time(?P<isutc>Z)?)?$/";
-
-        if (!preg_match($regex, $propertyValue, $matches)) {
-            throw new \InvalidArgumentException($propertyValue . ' is not a valid \DateTime or Date string');
-        }
-
-        if (!isset($matches['hour'])) {
-            // Date-only
-            return array(
-                self::DATE,
-                new \DateTime($matches['year'] . '-' . $matches['month'] . '-' . $matches['date'] . ' 00:00:00', new \DateTimeZone('UTC')),
-            );
-        }
-
-        $dateStr =
-            $matches['year'] .'-' .
-            $matches['month'] . '-' .
-            $matches['date'] . ' ' .
-            $matches['hour'] . ':' .
-            $matches['minute'] . ':' .
-            $matches['second'];
-
-        if (isset($matches['isutc'])) {
-            $dt = new \DateTime($dateStr,new \DateTimeZone('UTC'));
-            $dt->setTimeZone(new \DateTimeZone('UTC'));
-            return array(
-                self::UTC,
-                $dt
-            );
-        }
-
-        // Finding the timezone.
-        $tzid = $property['TZID'];
-        if (!$tzid) {
-            // This was a floating time string. This implies we use the
-            // timezone from date_default_timezone_set / date.timezone ini
-            // setting.
-            return array(
-                self::LOCAL,
-                new \DateTime($dateStr)
-            );
-        }
-
-        // To look up the timezone, we must first find the VCALENDAR component.
-        $root = $property;
-        while($root->parent) {
-            $root = $root->parent;
-        }
-        if ($root->name === 'VCALENDAR') {
-            $tz = VObject\TimeZoneUtil::getTimeZone((string)$tzid, $root);
-        } else {
-            $tz = VObject\TimeZoneUtil::getTimeZone((string)$tzid);
-        }
-
-        $dt = new \DateTime($dateStr, $tz);
-        $dt->setTimeZone($tz);
-
-        return array(
-            self::LOCALTZ,
-            $dt
-        );
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Property/MultiDateTime.php b/vendor/sabre/vobject/lib/Sabre/VObject/Property/MultiDateTime.php
deleted file mode 100644
index f01491b66..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Property/MultiDateTime.php
+++ /dev/null
@@ -1,180 +0,0 @@
-<?php
-
-namespace Sabre\VObject\Property;
-
-use Sabre\VObject;
-
-/**
- * Multi-DateTime property
- *
- * This element is used for iCalendar properties such as the EXDATE property.
- * It basically provides a few helper functions that make it easier to deal
- * with these. It supports both DATE-TIME and DATE values.
- *
- * In order to use this correctly, you must call setDateTimes and getDateTimes
- * to retrieve and modify dates respectively.
- *
- * If you use the 'value' or properties directly, this object does not keep
- * reference and results might appear incorrectly.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class MultiDateTime extends VObject\Property {
-
-    /**
-     * DateTime representation
-     *
-     * @var DateTime[]
-     */
-    protected $dateTimes;
-
-    /**
-     * dateType
-     *
-     * This is one of the Sabre\VObject\Property\DateTime constants.
-     *
-     * @var int
-     */
-    protected $dateType;
-
-    /**
-     * Updates the value
-     *
-     * @param array $dt Must be an array of DateTime objects.
-     * @param int $dateType
-     * @return void
-     */
-    public function setDateTimes(array $dt, $dateType = VObject\Property\DateTime::LOCALTZ) {
-
-        foreach($dt as $i)
-            if (!$i instanceof \DateTime)
-                throw new \InvalidArgumentException('You must pass an array of DateTime objects');
-
-        $this->offsetUnset('VALUE');
-        $this->offsetUnset('TZID');
-        switch($dateType) {
-
-            case DateTime::LOCAL :
-                $val = array();
-                foreach($dt as $i) {
-                    $val[] = $i->format('Ymd\\THis');
-                }
-                $this->setValue(implode(',',$val));
-                $this->offsetSet('VALUE','DATE-TIME');
-                break;
-            case DateTime::UTC :
-                $val = array();
-                foreach($dt as $i) {
-                    $i->setTimeZone(new \DateTimeZone('UTC'));
-                    $val[] = $i->format('Ymd\\THis\\Z');
-                }
-                $this->setValue(implode(',',$val));
-                $this->offsetSet('VALUE','DATE-TIME');
-                break;
-            case DateTime::LOCALTZ :
-                $val = array();
-                foreach($dt as $i) {
-                    $val[] = $i->format('Ymd\\THis');
-                }
-                $this->setValue(implode(',',$val));
-                $this->offsetSet('VALUE','DATE-TIME');
-                $this->offsetSet('TZID', $dt[0]->getTimeZone()->getName());
-                break;
-            case DateTime::DATE :
-                $val = array();
-                foreach($dt as $i) {
-                    $val[] = $i->format('Ymd');
-                }
-                $this->setValue(implode(',',$val));
-                $this->offsetSet('VALUE','DATE');
-                break;
-            default :
-                throw new \InvalidArgumentException('You must pass a valid dateType constant');
-
-        }
-        $this->dateTimes = $dt;
-        $this->dateType = $dateType;
-
-    }
-
-    /**
-     * Returns the current DateTime value.
-     *
-     * If no value was set, this method returns null.
-     *
-     * @return array|null
-     */
-    public function getDateTimes() {
-
-        if ($this->dateTimes)
-            return $this->dateTimes;
-
-        $dts = array();
-
-        if (!$this->value) {
-            $this->dateTimes = null;
-            $this->dateType = null;
-            return null;
-        }
-
-        foreach(explode(',',$this->value) as $val) {
-            list(
-                $type,
-                $dt
-            ) = DateTime::parseData($val, $this);
-            $dts[] = $dt;
-            $this->dateType = $type;
-        }
-        $this->dateTimes = $dts;
-        return $this->dateTimes;
-
-    }
-
-    /**
-     * Returns the type of Date format.
-     *
-     * This method returns one of the format constants. If no date was set,
-     * this method will return null.
-     *
-     * @return int|null
-     */
-    public function getDateType() {
-
-        if ($this->dateType)
-            return $this->dateType;
-
-        if (!$this->value) {
-            $this->dateTimes = null;
-            $this->dateType = null;
-            return null;
-        }
-
-        $dts = array();
-        foreach(explode(',',$this->value) as $val) {
-            list(
-                $type,
-                $dt
-            ) = DateTime::parseData($val, $this);
-            $dts[] = $dt;
-            $this->dateType = $type;
-        }
-        $this->dateTimes = $dts;
-        return $this->dateType;
-
-    }
-
-    /**
-     * This method will return true, if the property had a date and a time, as
-     * opposed to only a date.
-     *
-     * @return bool
-     */
-    public function hasTime() {
-
-        return $this->getDateType()!==DateTime::DATE;
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Reader.php b/vendor/sabre/vobject/lib/Sabre/VObject/Reader.php
deleted file mode 100644
index a001b2bf1..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Reader.php
+++ /dev/null
@@ -1,223 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * VCALENDAR/VCARD reader
- *
- * This class reads the vobject file, and returns a full element tree.
- *
- * TODO: this class currently completely works 'statically'. This is pointless,
- * and defeats OOP principals. Needs refactoring in a future version.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class Reader {
-
-    /**
-     * If this option is passed to the reader, it will be less strict about the
-     * validity of the lines.
-     *
-     * Currently using this option just means, that it will accept underscores
-     * in property names.
-     */
-    const OPTION_FORGIVING = 1;
-
-    /**
-     * If this option is turned on, any lines we cannot parse will be ignored
-     * by the reader.
-     */
-    const OPTION_IGNORE_INVALID_LINES = 2;
-
-    /**
-     * Parses the file and returns the top component
-     *
-     * The options argument is a bitfield. Pass any of the OPTIONS constant to
-     * alter the parsers' behaviour.
-     *
-     * @param string $data
-     * @param int $options
-     * @return Node
-     */
-    static function read($data, $options = 0) {
-
-        // Normalizing newlines
-        $data = str_replace(array("\r","\n\n"), array("\n","\n"), $data);
-
-        $lines = explode("\n", $data);
-
-        // Unfolding lines
-        $lines2 = array();
-        foreach($lines as $line) {
-
-            // Skipping empty lines
-            if (!$line) continue;
-
-            if ($line[0]===" " || $line[0]==="\t") {
-                $lines2[count($lines2)-1].=substr($line,1);
-            } else {
-                $lines2[] = $line;
-            }
-
-        }
-
-        unset($lines);
-
-        reset($lines2);
-
-        return self::readLine($lines2, $options);
-
-    }
-
-    /**
-     * Reads and parses a single line.
-     *
-     * This method receives the full array of lines. The array pointer is used
-     * to traverse.
-     *
-     * This method returns null if an invalid line was encountered, and the
-     * IGNORE_INVALID_LINES option was turned on.
-     *
-     * @param array $lines
-     * @param int $options See the OPTIONS constants.
-     * @return Node
-     */
-    static private function readLine(&$lines, $options = 0) {
-
-        $line = current($lines);
-        $lineNr = key($lines);
-        next($lines);
-
-        // Components
-        if (strtoupper(substr($line,0,6)) === "BEGIN:") {
-
-            $componentName = strtoupper(substr($line,6));
-            $obj = Component::create($componentName);
-
-            $nextLine = current($lines);
-
-            while(strtoupper(substr($nextLine,0,4))!=="END:") {
-
-                $parsedLine = self::readLine($lines, $options);
-                $nextLine = current($lines);
-
-                if (is_null($parsedLine)) {
-                    continue;
-                }
-                $obj->add($parsedLine);
-
-                if ($nextLine===false)
-                    throw new ParseException('Invalid VObject. Document ended prematurely.');
-
-            }
-
-            // Checking component name of the 'END:' line.
-            if (substr($nextLine,4)!==$obj->name) {
-                throw new ParseException('Invalid VObject, expected: "END:' . $obj->name . '" got: "' . $nextLine . '"');
-            }
-            next($lines);
-
-            return $obj;
-
-        }
-
-        // Properties
-        //$result = preg_match('/(?P<name>[A-Z0-9-]+)(?:;(?P<parameters>^(?<!:):))(.*)$/',$line,$matches);
-
-        if ($options & self::OPTION_FORGIVING) {
-            $token = '[A-Z0-9-\._]+';
-        } else {
-            $token = '[A-Z0-9-\.]+';
-        }
-        $parameters = "(?:;(?P<parameters>([^:^\"]|\"([^\"]*)\")*))?";
-        $regex = "/^(?P<name>$token)$parameters:(?P<value>.*)$/i";
-
-        $result = preg_match($regex,$line,$matches);
-
-        if (!$result) {
-            if ($options & self::OPTION_IGNORE_INVALID_LINES) {
-                return null;
-            } else {
-                throw new ParseException('Invalid VObject, line ' . ($lineNr+1) . ' did not follow the icalendar/vcard format');
-            }
-        }
-
-        $propertyName = strtoupper($matches['name']);
-        $propertyValue = preg_replace_callback('#(\\\\(\\\\|N|n))#',function($matches) {
-            if ($matches[2]==='n' || $matches[2]==='N') {
-                return "\n";
-            } else {
-                return $matches[2];
-            }
-        }, $matches['value']);
-
-        $obj = Property::create($propertyName, $propertyValue);
-
-        if ($matches['parameters']) {
-
-            foreach(self::readParameters($matches['parameters']) as $param) {
-                $obj->add($param);
-            }
-
-        }
-
-        return $obj;
-
-
-    }
-
-    /**
-     * Reads a parameter list from a property
-     *
-     * This method returns an array of Parameter
-     *
-     * @param string $parameters
-     * @return array
-     */
-    static private function readParameters($parameters) {
-
-        $token = '[A-Z0-9-]+';
-
-        $paramValue = '(?P<paramValue>[^\"^;]*|"[^"]*")';
-
-        $regex = "/(?<=^|;)(?P<paramName>$token)(=$paramValue(?=$|;))?/i";
-        preg_match_all($regex, $parameters, $matches,  PREG_SET_ORDER);
-
-        $params = array();
-        foreach($matches as $match) {
-
-            if (!isset($match['paramValue'])) {
-
-                $value = null;
-
-            } else {
-
-                $value = $match['paramValue'];
-
-                if (isset($value[0]) && $value[0]==='"') {
-                    // Stripping quotes, if needed
-                    $value = substr($value,1,strlen($value)-2);
-                }
-
-                $value = preg_replace_callback('#(\\\\(\\\\|N|n|;|,))#',function($matches) {
-                    if ($matches[2]==='n' || $matches[2]==='N') {
-                        return "\n";
-                    } else {
-                        return $matches[2];
-                    }
-                }, $value);
-
-            }
-
-            $params[] = new Parameter($match['paramName'], $value);
-
-        }
-
-        return $params;
-
-    }
-
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/RecurrenceIterator.php b/vendor/sabre/vobject/lib/Sabre/VObject/RecurrenceIterator.php
deleted file mode 100644
index 8bd4ed224..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/RecurrenceIterator.php
+++ /dev/null
@@ -1,1144 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * This class is used to determine new for a recurring event, when the next
- * events occur.
- *
- * This iterator may loop infinitely in the future, therefore it is important
- * that if you use this class, you set hard limits for the amount of iterations
- * you want to handle.
- *
- * Note that currently there is not full support for the entire iCalendar
- * specification, as it's very complex and contains a lot of permutations
- * that's not yet used very often in software.
- *
- * For the focus has been on features as they actually appear in Calendaring
- * software, but this may well get expanded as needed / on demand
- *
- * The following RRULE properties are supported
- *   * UNTIL
- *   * INTERVAL
- *   * COUNT
- *   * FREQ=DAILY
- *     * BYDAY
- *     * BYHOUR
- *   * FREQ=WEEKLY
- *     * BYDAY
- *     * BYHOUR
- *     * WKST
- *   * FREQ=MONTHLY
- *     * BYMONTHDAY
- *     * BYDAY
- *     * BYSETPOS
- *   * FREQ=YEARLY
- *     * BYMONTH
- *     * BYMONTHDAY (only if BYMONTH is also set)
- *     * BYDAY (only if BYMONTH is also set)
- *
- * Anything beyond this is 'undefined', which means that it may get ignored, or
- * you may get unexpected results. The effect is that in some applications the
- * specified recurrence may look incorrect, or is missing.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class RecurrenceIterator implements \Iterator {
-
-    /**
-     * The initial event date
-     *
-     * @var DateTime
-     */
-    public $startDate;
-
-    /**
-     * The end-date of the initial event
-     *
-     * @var DateTime
-     */
-    public $endDate;
-
-    /**
-     * The 'current' recurrence.
-     *
-     * This will be increased for every iteration.
-     *
-     * @var DateTime
-     */
-    public $currentDate;
-
-
-    /**
-     * List of dates that are excluded from the rules.
-     *
-     * This list contains the items that have been overriden by the EXDATE
-     * property.
-     *
-     * @var array
-     */
-    public $exceptionDates = array();
-
-    /**
-     * Base event
-     *
-     * @var Component\VEvent
-     */
-    public $baseEvent;
-
-    /**
-     * List of dates that are overridden by other events.
-     * Similar to $overriddenEvents, but this just contains the original dates.
-     *
-     * @var array
-     */
-    public $overriddenDates = array();
-
-    /**
-     * list of events that are 'overridden'.
-     *
-     * This is an array of Component\VEvent objects.
-     *
-     * @var array
-     */
-    public $overriddenEvents = array();
-
-    /**
-     * Frequency is one of: secondly, minutely, hourly, daily, weekly, monthly,
-     * yearly.
-     *
-     * @var string
-     */
-    public $frequency;
-
-    /**
-     * The last instance of this recurrence, inclusively
-     *
-     * @var DateTime|null
-     */
-    public $until;
-
-    /**
-     * The number of recurrences, or 'null' if infinitely recurring.
-     *
-     * @var int
-     */
-    public $count;
-
-    /**
-     * The interval.
-     *
-     * If for example frequency is set to daily, interval = 2 would mean every
-     * 2 days.
-     *
-     * @var int
-     */
-    public $interval = 1;
-
-    /**
-     * Which seconds to recur.
-     *
-     * This is an array of integers (between 0 and 60)
-     *
-     * @var array
-     */
-    public $bySecond;
-
-    /**
-     * Which minutes to recur
-     *
-     * This is an array of integers (between 0 and 59)
-     *
-     * @var array
-     */
-    public $byMinute;
-
-    /**
-     * Which hours to recur
-     *
-     * This is an array of integers (between 0 and 23)
-     *
-     * @var array
-     */
-    public $byHour;
-
-    /**
-     * Which weekdays to recur.
-     *
-     * This is an array of weekdays
-     *
-     * This may also be preceeded by a positive or negative integer. If present,
-     * this indicates the nth occurrence of a specific day within the monthly or
-     * yearly rrule. For instance, -2TU indicates the second-last tuesday of
-     * the month, or year.
-     *
-     * @var array
-     */
-    public $byDay;
-
-    /**
-     * Which days of the month to recur
-     *
-     * This is an array of days of the months (1-31). The value can also be
-     * negative. -5 for instance means the 5th last day of the month.
-     *
-     * @var array
-     */
-    public $byMonthDay;
-
-    /**
-     * Which days of the year to recur.
-     *
-     * This is an array with days of the year (1 to 366). The values can also
-     * be negative. For instance, -1 will always represent the last day of the
-     * year. (December 31st).
-     *
-     * @var array
-     */
-    public $byYearDay;
-
-    /**
-     * Which week numbers to recur.
-     *
-     * This is an array of integers from 1 to 53. The values can also be
-     * negative. -1 will always refer to the last week of the year.
-     *
-     * @var array
-     */
-    public $byWeekNo;
-
-    /**
-     * Which months to recur
-     *
-     * This is an array of integers from 1 to 12.
-     *
-     * @var array
-     */
-    public $byMonth;
-
-    /**
-     * Which items in an existing st to recur.
-     *
-     * These numbers work together with an existing by* rule. It specifies
-     * exactly which items of the existing by-rule to filter.
-     *
-     * Valid values are 1 to 366 and -1 to -366. As an example, this can be
-     * used to recur the last workday of the month.
-     *
-     * This would be done by setting frequency to 'monthly', byDay to
-     * 'MO,TU,WE,TH,FR' and bySetPos to -1.
-     *
-     * @var array
-     */
-    public $bySetPos;
-
-    /**
-     * When a week starts
-     *
-     * @var string
-     */
-    public $weekStart = 'MO';
-
-    /**
-     * The current item in the list
-     *
-     * @var int
-     */
-    public $counter = 0;
-
-    /**
-     * Simple mapping from iCalendar day names to day numbers
-     *
-     * @var array
-     */
-    private $dayMap = array(
-        'SU' => 0,
-        'MO' => 1,
-        'TU' => 2,
-        'WE' => 3,
-        'TH' => 4,
-        'FR' => 5,
-        'SA' => 6,
-    );
-
-    /**
-     * Mappings between the day number and english day name.
-     *
-     * @var array
-     */
-    private $dayNames = array(
-        0 => 'Sunday',
-        1 => 'Monday',
-        2 => 'Tuesday',
-        3 => 'Wednesday',
-        4 => 'Thursday',
-        5 => 'Friday',
-        6 => 'Saturday',
-    );
-
-    /**
-     * If the current iteration of the event is an overriden event, this
-     * property will hold the VObject
-     *
-     * @var Component
-     */
-    private $currentOverriddenEvent;
-
-    /**
-     * This property may contain the date of the next not-overridden event.
-     * This date is calculated sometimes a bit early, before overridden events
-     * are evaluated.
-     *
-     * @var DateTime
-     */
-    private $nextDate;
-
-    /**
-     * This counts the number of overridden events we've handled so far
-     *
-     * @var int
-     */
-    private $handledOverridden = 0;
-
-    /**
-     * Creates the iterator
-     *
-     * You should pass a VCALENDAR component, as well as the UID of the event
-     * we're going to traverse.
-     *
-     * @param Component $vcal
-     * @param string|null $uid
-     */
-    public function __construct(Component $vcal, $uid=null) {
-
-        if (is_null($uid)) {
-            if ($vcal->name === 'VCALENDAR') {
-                throw new \InvalidArgumentException('If you pass a VCALENDAR object, you must pass a uid argument as well');
-            }
-            $components = array($vcal);
-            $uid = (string)$vcal->uid;
-        } else {
-            $components = $vcal->select('VEVENT');
-        }
-        foreach($components as $component) {
-            if ((string)$component->uid == $uid) {
-                if (isset($component->{'RECURRENCE-ID'})) {
-                    $this->overriddenEvents[$component->DTSTART->getDateTime()->getTimeStamp()] = $component;
-                    $this->overriddenDates[] = $component->{'RECURRENCE-ID'}->getDateTime();
-                } else {
-                    $this->baseEvent = $component;
-                }
-            }
-        }
-
-        ksort($this->overriddenEvents);
-
-        if (!$this->baseEvent) {
-            throw new \InvalidArgumentException('Could not find a base event with uid: ' . $uid);
-        }
-
-        $this->startDate = clone $this->baseEvent->DTSTART->getDateTime();
-
-        $this->endDate = null;
-        if (isset($this->baseEvent->DTEND)) {
-            $this->endDate = clone $this->baseEvent->DTEND->getDateTime();
-        } else {
-            $this->endDate = clone $this->startDate;
-            if (isset($this->baseEvent->DURATION)) {
-                $this->endDate->add(DateTimeParser::parse($this->baseEvent->DURATION->value));
-            } elseif ($this->baseEvent->DTSTART->getDateType()===Property\DateTime::DATE) {
-                $this->endDate->modify('+1 day');
-            }
-        }
-        $this->currentDate = clone $this->startDate;
-
-        $rrule = (string)$this->baseEvent->RRULE;
-
-        $parts = explode(';', $rrule);
-
-        // If no rrule was specified, we create a default setting
-        if (!$rrule) {
-            $this->frequency = 'daily';
-            $this->count = 1;
-        } else foreach($parts as $part) {
-
-            list($key, $value) = explode('=', $part, 2);
-
-            switch(strtoupper($key)) {
-
-                case 'FREQ' :
-                    if (!in_array(
-                        strtolower($value),
-                        array('secondly','minutely','hourly','daily','weekly','monthly','yearly')
-                    )) {
-                        throw new \InvalidArgumentException('Unknown value for FREQ=' . strtoupper($value));
-
-                    }
-                    $this->frequency = strtolower($value);
-                    break;
-
-                case 'UNTIL' :
-                    $this->until = DateTimeParser::parse($value);
-
-                    // In some cases events are generated with an UNTIL=
-                    // parameter before the actual start of the event.
-                    //
-                    // Not sure why this is happening. We assume that the
-                    // intention was that the event only recurs once.
-                    //
-                    // So we are modifying the parameter so our code doesn't
-                    // break.
-                    if($this->until < $this->baseEvent->DTSTART->getDateTime()) {
-                        $this->until = $this->baseEvent->DTSTART->getDateTime();
-                    }
-                    break;
-
-                case 'COUNT' :
-                    $this->count = (int)$value;
-                    break;
-
-                case 'INTERVAL' :
-                    $this->interval = (int)$value;
-                    if ($this->interval < 1) {
-                        throw new \InvalidArgumentException('INTERVAL in RRULE must be a positive integer!');
-                    }
-                    break;
-
-                case 'BYSECOND' :
-                    $this->bySecond = explode(',', $value);
-                    break;
-
-                case 'BYMINUTE' :
-                    $this->byMinute = explode(',', $value);
-                    break;
-
-                case 'BYHOUR' :
-                    $this->byHour = explode(',', $value);
-                    break;
-
-                case 'BYDAY' :
-                    $this->byDay = explode(',', strtoupper($value));
-                    break;
-
-                case 'BYMONTHDAY' :
-                    $this->byMonthDay = explode(',', $value);
-                    break;
-
-                case 'BYYEARDAY' :
-                    $this->byYearDay = explode(',', $value);
-                    break;
-
-                case 'BYWEEKNO' :
-                    $this->byWeekNo = explode(',', $value);
-                    break;
-
-                case 'BYMONTH' :
-                    $this->byMonth = explode(',', $value);
-                    break;
-
-                case 'BYSETPOS' :
-                    $this->bySetPos = explode(',', $value);
-                    break;
-
-                case 'WKST' :
-                    $this->weekStart = strtoupper($value);
-                    break;
-
-            }
-
-        }
-
-        // Parsing exception dates
-        if (isset($this->baseEvent->EXDATE)) {
-            foreach($this->baseEvent->EXDATE as $exDate) {
-
-                foreach(explode(',', (string)$exDate) as $exceptionDate) {
-
-                    $this->exceptionDates[] =
-                        DateTimeParser::parse($exceptionDate, $this->startDate->getTimeZone());
-
-                }
-
-            }
-
-        }
-
-    }
-
-    /**
-     * Returns the current item in the list
-     *
-     * @return DateTime
-     */
-    public function current() {
-
-        if (!$this->valid()) return null;
-        return clone $this->currentDate;
-
-    }
-
-    /**
-     * This method returns the startdate for the current iteration of the
-     * event.
-     *
-     * @return DateTime
-     */
-    public function getDtStart() {
-
-        if (!$this->valid()) return null;
-        return clone $this->currentDate;
-
-    }
-
-    /**
-     * This method returns the enddate for the current iteration of the
-     * event.
-     *
-     * @return DateTime
-     */
-    public function getDtEnd() {
-
-        if (!$this->valid()) return null;
-        $dtEnd = clone $this->currentDate;
-        $dtEnd->add( $this->startDate->diff( $this->endDate ) );
-        return clone $dtEnd;
-
-    }
-
-    /**
-     * Returns a VEVENT object with the updated start and end date.
-     *
-     * Any recurrence information is removed, and this function may return an
-     * 'overridden' event instead.
-     *
-     * This method always returns a cloned instance.
-     *
-     * @return Component\VEvent
-     */
-    public function getEventObject() {
-
-        if ($this->currentOverriddenEvent) {
-            return clone $this->currentOverriddenEvent;
-        }
-        $event = clone $this->baseEvent;
-        unset($event->RRULE);
-        unset($event->EXDATE);
-        unset($event->RDATE);
-        unset($event->EXRULE);
-
-        $event->DTSTART->setDateTime($this->getDTStart(), $event->DTSTART->getDateType());
-        if (isset($event->DTEND)) {
-            $event->DTEND->setDateTime($this->getDtEnd(), $event->DTSTART->getDateType());
-        }
-        if ($this->counter > 0) {
-            $event->{'RECURRENCE-ID'} = (string)$event->DTSTART;
-        }
-
-        return $event;
-
-    }
-
-    /**
-     * Returns the current item number
-     *
-     * @return int
-     */
-    public function key() {
-
-        return $this->counter;
-
-    }
-
-    /**
-     * Whether or not there is a 'next item'
-     *
-     * @return bool
-     */
-    public function valid() {
-
-        if (!is_null($this->count)) {
-            return $this->counter < $this->count;
-        }
-        if (!is_null($this->until) && $this->currentDate > $this->until) {
-
-            // Need to make sure there's no overridden events past the
-            // until date.
-            foreach($this->overriddenEvents as $overriddenEvent) {
-
-                if ($overriddenEvent->DTSTART->getDateTime() >= $this->currentDate) {
-
-                    return true;
-                }
-            }
-            return false;
-        }
-        return true;
-
-    }
-
-    /**
-     * Resets the iterator
-     *
-     * @return void
-     */
-    public function rewind() {
-
-        $this->currentDate = clone $this->startDate;
-        $this->counter = 0;
-
-    }
-
-    /**
-     * This method allows you to quickly go to the next occurrence after the
-     * specified date.
-     *
-     * Note that this checks the current 'endDate', not the 'stardDate'. This
-     * means that if you forward to January 1st, the iterator will stop at the
-     * first event that ends *after* January 1st.
-     *
-     * @param DateTime $dt
-     * @return void
-     */
-    public function fastForward(\DateTime $dt) {
-
-        while($this->valid() && $this->getDTEnd() <= $dt) {
-            $this->next();
-        }
-
-    }
-
-    /**
-     * Returns true if this recurring event never ends.
-     *
-     * @return bool
-     */
-    public function isInfinite() {
-
-        return !$this->count && !$this->until;
-
-    }
-
-    /**
-     * Goes on to the next iteration
-     *
-     * @return void
-     */
-    public function next() {
-
-        $previousStamp = $this->currentDate->getTimeStamp();
-
-        // Finding the next overridden event in line, and storing that for
-        // later use.
-        $overriddenEvent = null;
-        $overriddenDate = null;
-        $this->currentOverriddenEvent = null;
-
-        foreach($this->overriddenEvents as $index=>$event) {
-            if ($index > $previousStamp) {
-                $overriddenEvent = $event;
-                $overriddenDate = clone $event->DTSTART->getDateTime();
-                break;
-            }
-        }
-
-        // If we have a stored 'next date', we will use that.
-        if ($this->nextDate) {
-            if (!$overriddenDate || $this->nextDate < $overriddenDate) {
-                $this->currentDate = $this->nextDate;
-                $currentStamp = $this->currentDate->getTimeStamp();
-                $this->nextDate = null;
-            } else {
-                $this->currentDate = clone $overriddenDate;
-                $this->currentOverriddenEvent = $overriddenEvent;
-            }
-            $this->counter++;
-            return;
-        }
-
-        while(true) {
-
-            // Otherwise, we find the next event in the normal RRULE
-            // sequence.
-            switch($this->frequency) {
-
-                case 'hourly' :
-                    $this->nextHourly();
-                    break;
-
-                case 'daily' :
-                    $this->nextDaily();
-                    break;
-
-                case 'weekly' :
-                    $this->nextWeekly();
-                    break;
-
-                case 'monthly' :
-                    $this->nextMonthly();
-                    break;
-
-                case 'yearly' :
-                    $this->nextYearly();
-                    break;
-
-            }
-            $currentStamp = $this->currentDate->getTimeStamp();
-
-
-            // Checking exception dates
-            foreach($this->exceptionDates as $exceptionDate) {
-                if ($this->currentDate == $exceptionDate) {
-                    $this->counter++;
-                    continue 2;
-                }
-            }
-            foreach($this->overriddenDates as $check) {
-                if ($this->currentDate == $check) {
-                    continue 2;
-                }
-            }
-            break;
-
-        }
-
-
-
-        // Is the date we have actually higher than the next overiddenEvent?
-        if ($overriddenDate && $this->currentDate > $overriddenDate) {
-            $this->nextDate = clone $this->currentDate;
-            $this->currentDate = clone $overriddenDate;
-            $this->currentOverriddenEvent = $overriddenEvent;
-            $this->handledOverridden++;
-        }
-        $this->counter++;
-
-
-        /*
-         * If we have overridden events left in the queue, but our counter is
-         * running out, we should grab one of those.
-         */
-        if (!is_null($overriddenEvent) && !is_null($this->count) && count($this->overriddenEvents) - $this->handledOverridden >= ($this->count - $this->counter)) {
-
-            $this->currentOverriddenEvent = $overriddenEvent;
-            $this->currentDate = clone $overriddenDate;
-            $this->handledOverridden++;
-
-        }
-
-    }
-
-    /**
-     * Does the processing for advancing the iterator for hourly frequency.
-     *
-     * @return void
-     */
-    protected function nextHourly() {
-
-        if (!$this->byHour) {
-            $this->currentDate->modify('+' . $this->interval . ' hours');
-            return;
-        }
-    }
-
-    /**
-     * Does the processing for advancing the iterator for daily frequency.
-     *
-     * @return void
-     */
-    protected function nextDaily() {
-
-        if (!$this->byHour && !$this->byDay) {
-            $this->currentDate->modify('+' . $this->interval . ' days');
-            return;
-        }
-
-        if (isset($this->byHour)) {
-            $recurrenceHours = $this->getHours();
-        }
-
-        if (isset($this->byDay)) {
-            $recurrenceDays = $this->getDays();
-        }
-
-        do {
-
-            if ($this->byHour) {
-                if ($this->currentDate->format('G') == '23') {
-                    // to obey the interval rule
-                    $this->currentDate->modify('+' . $this->interval-1 . ' days');
-                }
-
-                $this->currentDate->modify('+1 hours');
-
-            } else {
-                $this->currentDate->modify('+' . $this->interval . ' days');
-
-            }
-
-            // Current day of the week
-            $currentDay = $this->currentDate->format('w');
-
-            // Current hour of the day
-            $currentHour = $this->currentDate->format('G');
-
-        } while (($this->byDay && !in_array($currentDay, $recurrenceDays)) || ($this->byHour && !in_array($currentHour, $recurrenceHours)));
-
-    }
-
-    /**
-     * Does the processing for advancing the iterator for weekly frequency.
-     *
-     * @return void
-     */
-    protected function nextWeekly() {
-
-        if (!$this->byHour && !$this->byDay) {
-            $this->currentDate->modify('+' . $this->interval . ' weeks');
-            return;
-        }
-
-        if ($this->byHour) {
-            $recurrenceHours = $this->getHours();
-        }
-
-        if ($this->byDay) {
-            $recurrenceDays = $this->getDays();
-        }
-
-        // First day of the week:
-        $firstDay = $this->dayMap[$this->weekStart];
-
-        do {
-
-            if ($this->byHour) {
-                $this->currentDate->modify('+1 hours');
-            } else {
-                $this->currentDate->modify('+1 days');
-            }
-
-            // Current day of the week
-            $currentDay = (int) $this->currentDate->format('w');
-
-            // Current hour of the day
-            $currentHour = (int) $this->currentDate->format('G');
-
-            // We need to roll over to the next week
-            if ($currentDay === $firstDay && (!$this->byHour || $currentHour == '0')) {
-                $this->currentDate->modify('+' . $this->interval-1 . ' weeks');
-
-                // We need to go to the first day of this week, but only if we
-                // are not already on this first day of this week.
-                if($this->currentDate->format('w') != $firstDay) {
-                    $this->currentDate->modify('last ' . $this->dayNames[$this->dayMap[$this->weekStart]]);
-                }
-            }
-
-            // We have a match
-        } while (($this->byDay && !in_array($currentDay, $recurrenceDays)) || ($this->byHour && !in_array($currentHour, $recurrenceHours)));
-    }
-
-    /**
-     * Does the processing for advancing the iterator for monthly frequency.
-     *
-     * @return void
-     */
-    protected function nextMonthly() {
-
-        $currentDayOfMonth = $this->currentDate->format('j');
-        if (!$this->byMonthDay && !$this->byDay) {
-
-            // If the current day is higher than the 28th, rollover can
-            // occur to the next month. We Must skip these invalid
-            // entries.
-            if ($currentDayOfMonth < 29) {
-                $this->currentDate->modify('+' . $this->interval . ' months');
-            } else {
-                $increase = 0;
-                do {
-                    $increase++;
-                    $tempDate = clone $this->currentDate;
-                    $tempDate->modify('+ ' . ($this->interval*$increase) . ' months');
-                } while ($tempDate->format('j') != $currentDayOfMonth);
-                $this->currentDate = $tempDate;
-            }
-            return;
-        }
-
-        while(true) {
-
-            $occurrences = $this->getMonthlyOccurrences();
-
-            foreach($occurrences as $occurrence) {
-
-                // The first occurrence thats higher than the current
-                // day of the month wins.
-                if ($occurrence > $currentDayOfMonth) {
-                    break 2;
-                }
-
-            }
-
-            // If we made it all the way here, it means there were no
-            // valid occurrences, and we need to advance to the next
-            // month.
-            $this->currentDate->modify('first day of this month');
-            $this->currentDate->modify('+ ' . $this->interval . ' months');
-
-            // This goes to 0 because we need to start counting at hte
-            // beginning.
-            $currentDayOfMonth = 0;
-
-        }
-
-        $this->currentDate->setDate($this->currentDate->format('Y'), $this->currentDate->format('n'), $occurrence);
-
-    }
-
-    /**
-     * Does the processing for advancing the iterator for yearly frequency.
-     *
-     * @return void
-     */
-    protected function nextYearly() {
-
-        $currentMonth = $this->currentDate->format('n');
-        $currentYear = $this->currentDate->format('Y');
-        $currentDayOfMonth = $this->currentDate->format('j');
-
-        // No sub-rules, so we just advance by year
-        if (!$this->byMonth) {
-
-            // Unless it was a leap day!
-            if ($currentMonth==2 && $currentDayOfMonth==29) {
-
-                $counter = 0;
-                do {
-                    $counter++;
-                    // Here we increase the year count by the interval, until
-                    // we hit a date that's also in a leap year.
-                    //
-                    // We could just find the next interval that's dividable by
-                    // 4, but that would ignore the rule that there's no leap
-                    // year every year that's dividable by a 100, but not by
-                    // 400. (1800, 1900, 2100). So we just rely on the datetime
-                    // functions instead.
-                    $nextDate = clone $this->currentDate;
-                    $nextDate->modify('+ ' . ($this->interval*$counter) . ' years');
-                } while ($nextDate->format('n')!=2);
-                $this->currentDate = $nextDate;
-
-                return;
-
-            }
-
-            // The easiest form
-            $this->currentDate->modify('+' . $this->interval . ' years');
-            return;
-
-        }
-
-        $currentMonth = $this->currentDate->format('n');
-        $currentYear = $this->currentDate->format('Y');
-        $currentDayOfMonth = $this->currentDate->format('j');
-
-        $advancedToNewMonth = false;
-
-        // If we got a byDay or getMonthDay filter, we must first expand
-        // further.
-        if ($this->byDay || $this->byMonthDay) {
-
-            while(true) {
-
-                $occurrences = $this->getMonthlyOccurrences();
-
-                foreach($occurrences as $occurrence) {
-
-                    // The first occurrence that's higher than the current
-                    // day of the month wins.
-                    // If we advanced to the next month or year, the first
-                    // occurrence is always correct.
-                    if ($occurrence > $currentDayOfMonth || $advancedToNewMonth) {
-                        break 2;
-                    }
-
-                }
-
-                // If we made it here, it means we need to advance to
-                // the next month or year.
-                $currentDayOfMonth = 1;
-                $advancedToNewMonth = true;
-                do {
-
-                    $currentMonth++;
-                    if ($currentMonth>12) {
-                        $currentYear+=$this->interval;
-                        $currentMonth = 1;
-                    }
-                } while (!in_array($currentMonth, $this->byMonth));
-
-                $this->currentDate->setDate($currentYear, $currentMonth, $currentDayOfMonth);
-
-            }
-
-            // If we made it here, it means we got a valid occurrence
-            $this->currentDate->setDate($currentYear, $currentMonth, $occurrence);
-            return;
-
-        } else {
-
-            // These are the 'byMonth' rules, if there are no byDay or
-            // byMonthDay sub-rules.
-            do {
-
-                $currentMonth++;
-                if ($currentMonth>12) {
-                    $currentYear+=$this->interval;
-                    $currentMonth = 1;
-                }
-            } while (!in_array($currentMonth, $this->byMonth));
-            $this->currentDate->setDate($currentYear, $currentMonth, $currentDayOfMonth);
-
-            return;
-
-        }
-
-    }
-
-    /**
-     * Returns all the occurrences for a monthly frequency with a 'byDay' or
-     * 'byMonthDay' expansion for the current month.
-     *
-     * The returned list is an array of integers with the day of month (1-31).
-     *
-     * @return array
-     */
-    protected function getMonthlyOccurrences() {
-
-        $startDate = clone $this->currentDate;
-
-        $byDayResults = array();
-
-        // Our strategy is to simply go through the byDays, advance the date to
-        // that point and add it to the results.
-        if ($this->byDay) foreach($this->byDay as $day) {
-
-            $dayName = $this->dayNames[$this->dayMap[substr($day,-2)]];
-
-            // Dayname will be something like 'wednesday'. Now we need to find
-            // all wednesdays in this month.
-            $dayHits = array();
-
-            $checkDate = clone $startDate;
-            $checkDate->modify('first day of this month');
-            $checkDate->modify($dayName);
-
-            do {
-                $dayHits[] = $checkDate->format('j');
-                $checkDate->modify('next ' . $dayName);
-            } while ($checkDate->format('n') === $startDate->format('n'));
-
-            // So now we have 'all wednesdays' for month. It is however
-            // possible that the user only really wanted the 1st, 2nd or last
-            // wednesday.
-            if (strlen($day)>2) {
-                $offset = (int)substr($day,0,-2);
-
-                if ($offset>0) {
-                    // It is possible that the day does not exist, such as a
-                    // 5th or 6th wednesday of the month.
-                    if (isset($dayHits[$offset-1])) {
-                        $byDayResults[] = $dayHits[$offset-1];
-                    }
-                } else {
-
-                    // if it was negative we count from the end of the array
-                    $byDayResults[] = $dayHits[count($dayHits) + $offset];
-                }
-            } else {
-                // There was no counter (first, second, last wednesdays), so we
-                // just need to add the all to the list).
-                $byDayResults = array_merge($byDayResults, $dayHits);
-
-            }
-
-        }
-
-        $byMonthDayResults = array();
-        if ($this->byMonthDay) foreach($this->byMonthDay as $monthDay) {
-
-            // Removing values that are out of range for this month
-            if ($monthDay > $startDate->format('t') ||
-                $monthDay < 0-$startDate->format('t')) {
-                    continue;
-            }
-            if ($monthDay>0) {
-                $byMonthDayResults[] = $monthDay;
-            } else {
-                // Negative values
-                $byMonthDayResults[] = $startDate->format('t') + 1 + $monthDay;
-            }
-        }
-
-        // If there was just byDay or just byMonthDay, they just specify our
-        // (almost) final list. If both were provided, then byDay limits the
-        // list.
-        if ($this->byMonthDay && $this->byDay) {
-            $result = array_intersect($byMonthDayResults, $byDayResults);
-        } elseif ($this->byMonthDay) {
-            $result = $byMonthDayResults;
-        } else {
-            $result = $byDayResults;
-        }
-        $result = array_unique($result);
-        sort($result, SORT_NUMERIC);
-
-        // The last thing that needs checking is the BYSETPOS. If it's set, it
-        // means only certain items in the set survive the filter.
-        if (!$this->bySetPos) {
-            return $result;
-        }
-
-        $filteredResult = array();
-        foreach($this->bySetPos as $setPos) {
-
-            if ($setPos<0) {
-                $setPos = count($result)-($setPos+1);
-            }
-            if (isset($result[$setPos-1])) {
-                $filteredResult[] = $result[$setPos-1];
-            }
-        }
-
-        sort($filteredResult, SORT_NUMERIC);
-        return $filteredResult;
-
-    }
-
-    protected function getHours()
-    {
-        $recurrenceHours = array();
-        foreach($this->byHour as $byHour) {
-            $recurrenceHours[] = $byHour;
-        }
-
-        return $recurrenceHours;
-    }
-
-    protected function getDays()
-    {
-        $recurrenceDays = array();
-        foreach($this->byDay as $byDay) {
-
-            // The day may be preceeded with a positive (+n) or
-            // negative (-n) integer. However, this does not make
-            // sense in 'weekly' so we ignore it here.
-            $recurrenceDays[] = $this->dayMap[substr($byDay,-2)];
-
-        }
-
-        return $recurrenceDays;
-    }
-}
-
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/StringUtil.php b/vendor/sabre/vobject/lib/Sabre/VObject/StringUtil.php
deleted file mode 100644
index ea88e1e86..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/StringUtil.php
+++ /dev/null
@@ -1,61 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * Useful utilities for working with various strings.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class StringUtil {
-
-    /**
-     * Returns true or false depending on if a string is valid UTF-8
-     *
-     * @param string $str
-     * @return bool
-     */
-    static function isUTF8($str) {
-
-        // First check.. mb_check_encoding
-        if (!mb_check_encoding($str, 'UTF-8')) {
-            return false;
-        }
-
-        // Control characters
-        if (preg_match('%(?:[\x00-\x08\x0B-\x0C\x0E\x0F])%', $str)) {
-            return false;
-        }
-
-        return true;
-
-    }
-
-    /**
-     * This method tries its best to convert the input string to UTF-8.
-     *
-     * Currently only ISO-5991-1 input and UTF-8 input is supported, but this
-     * may be expanded upon if we receive other examples.
-     *
-     * @param string $str
-     * @return string
-     */
-    static function convertToUTF8($str) {
-
-        $encoding = mb_detect_encoding($str , array('UTF-8','ISO-8859-1'), true);
-
-        if ($encoding === 'ISO-8859-1') {
-            $newStr = utf8_encode($str);
-        } else {
-            $newStr = $str;
-        }
-
-        // Removing any control characters
-        return (preg_replace('%(?:[\x00-\x08\x0B-\x0C\x0E\x0F])%', '', $newStr));
-
-    }
-
-}
-
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/TimeZoneUtil.php b/vendor/sabre/vobject/lib/Sabre/VObject/TimeZoneUtil.php
deleted file mode 100644
index c009a6af0..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/TimeZoneUtil.php
+++ /dev/null
@@ -1,527 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * Time zone name translation
- *
- * This file translates well-known time zone names into "Olson database" time zone names.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Frank Edelhaeuser (fedel@users.sourceforge.net)
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class TimeZoneUtil {
-
-    public static $map = array(
-
-        // from http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/zone_tzid.html
-        // snapshot taken on 2012/01/16
-
-        // windows
-        'AUS Central Standard Time'=>'Australia/Darwin',
-        'AUS Eastern Standard Time'=>'Australia/Sydney',
-        'Afghanistan Standard Time'=>'Asia/Kabul',
-        'Alaskan Standard Time'=>'America/Anchorage',
-        'Arab Standard Time'=>'Asia/Riyadh',
-        'Arabian Standard Time'=>'Asia/Dubai',
-        'Arabic Standard Time'=>'Asia/Baghdad',
-        'Argentina Standard Time'=>'America/Buenos_Aires',
-        'Armenian Standard Time'=>'Asia/Yerevan',
-        'Atlantic Standard Time'=>'America/Halifax',
-        'Azerbaijan Standard Time'=>'Asia/Baku',
-        'Azores Standard Time'=>'Atlantic/Azores',
-        'Bangladesh Standard Time'=>'Asia/Dhaka',
-        'Canada Central Standard Time'=>'America/Regina',
-        'Cape Verde Standard Time'=>'Atlantic/Cape_Verde',
-        'Caucasus Standard Time'=>'Asia/Yerevan',
-        'Cen. Australia Standard Time'=>'Australia/Adelaide',
-        'Central America Standard Time'=>'America/Guatemala',
-        'Central Asia Standard Time'=>'Asia/Almaty',
-        'Central Brazilian Standard Time'=>'America/Cuiaba',
-        'Central Europe Standard Time'=>'Europe/Budapest',
-        'Central European Standard Time'=>'Europe/Warsaw',
-        'Central Pacific Standard Time'=>'Pacific/Guadalcanal',
-        'Central Standard Time'=>'America/Chicago',
-        'Central Standard Time (Mexico)'=>'America/Mexico_City',
-        'China Standard Time'=>'Asia/Shanghai',
-        'Dateline Standard Time'=>'Etc/GMT+12',
-        'E. Africa Standard Time'=>'Africa/Nairobi',
-        'E. Australia Standard Time'=>'Australia/Brisbane',
-        'E. Europe Standard Time'=>'Europe/Minsk',
-        'E. South America Standard Time'=>'America/Sao_Paulo',
-        'Eastern Standard Time'=>'America/New_York',
-        'Egypt Standard Time'=>'Africa/Cairo',
-        'Ekaterinburg Standard Time'=>'Asia/Yekaterinburg',
-        'FLE Standard Time'=>'Europe/Kiev',
-        'Fiji Standard Time'=>'Pacific/Fiji',
-        'GMT Standard Time'=>'Europe/London',
-        'GTB Standard Time'=>'Europe/Istanbul',
-        'Georgian Standard Time'=>'Asia/Tbilisi',
-        'Greenland Standard Time'=>'America/Godthab',
-        'Greenwich Standard Time'=>'Atlantic/Reykjavik',
-        'Hawaiian Standard Time'=>'Pacific/Honolulu',
-        'India Standard Time'=>'Asia/Calcutta',
-        'Iran Standard Time'=>'Asia/Tehran',
-        'Israel Standard Time'=>'Asia/Jerusalem',
-        'Jordan Standard Time'=>'Asia/Amman',
-        'Kamchatka Standard Time'=>'Asia/Kamchatka',
-        'Korea Standard Time'=>'Asia/Seoul',
-        'Magadan Standard Time'=>'Asia/Magadan',
-        'Mauritius Standard Time'=>'Indian/Mauritius',
-        'Mexico Standard Time'=>'America/Mexico_City',
-        'Mexico Standard Time 2'=>'America/Chihuahua',
-        'Mid-Atlantic Standard Time'=>'Etc/GMT-2',
-        'Middle East Standard Time'=>'Asia/Beirut',
-        'Montevideo Standard Time'=>'America/Montevideo',
-        'Morocco Standard Time'=>'Africa/Casablanca',
-        'Mountain Standard Time'=>'America/Denver',
-        'Mountain Standard Time (Mexico)'=>'America/Chihuahua',
-        'Myanmar Standard Time'=>'Asia/Rangoon',
-        'N. Central Asia Standard Time'=>'Asia/Novosibirsk',
-        'Namibia Standard Time'=>'Africa/Windhoek',
-        'Nepal Standard Time'=>'Asia/Katmandu',
-        'New Zealand Standard Time'=>'Pacific/Auckland',
-        'Newfoundland Standard Time'=>'America/St_Johns',
-        'North Asia East Standard Time'=>'Asia/Irkutsk',
-        'North Asia Standard Time'=>'Asia/Krasnoyarsk',
-        'Pacific SA Standard Time'=>'America/Santiago',
-        'Pacific Standard Time'=>'America/Los_Angeles',
-        'Pacific Standard Time (Mexico)'=>'America/Santa_Isabel',
-        'Pakistan Standard Time'=>'Asia/Karachi',
-        'Paraguay Standard Time'=>'America/Asuncion',
-        'Romance Standard Time'=>'Europe/Paris',
-        'Russian Standard Time'=>'Europe/Moscow',
-        'SA Eastern Standard Time'=>'America/Cayenne',
-        'SA Pacific Standard Time'=>'America/Bogota',
-        'SA Western Standard Time'=>'America/La_Paz',
-        'SE Asia Standard Time'=>'Asia/Bangkok',
-        'Samoa Standard Time'=>'Pacific/Apia',
-        'Singapore Standard Time'=>'Asia/Singapore',
-        'South Africa Standard Time'=>'Africa/Johannesburg',
-        'Sri Lanka Standard Time'=>'Asia/Colombo',
-        'Syria Standard Time'=>'Asia/Damascus',
-        'Taipei Standard Time'=>'Asia/Taipei',
-        'Tasmania Standard Time'=>'Australia/Hobart',
-        'Tokyo Standard Time'=>'Asia/Tokyo',
-        'Tonga Standard Time'=>'Pacific/Tongatapu',
-        'US Eastern Standard Time'=>'America/Indianapolis',
-        'US Mountain Standard Time'=>'America/Phoenix',
-        'UTC+12'=>'Etc/GMT-12',
-        'UTC-02'=>'Etc/GMT+2',
-        'UTC-11'=>'Etc/GMT+11',
-        'Ulaanbaatar Standard Time'=>'Asia/Ulaanbaatar',
-        'Venezuela Standard Time'=>'America/Caracas',
-        'Vladivostok Standard Time'=>'Asia/Vladivostok',
-        'W. Australia Standard Time'=>'Australia/Perth',
-        'W. Central Africa Standard Time'=>'Africa/Lagos',
-        'W. Europe Standard Time'=>'Europe/Berlin',
-        'West Asia Standard Time'=>'Asia/Tashkent',
-        'West Pacific Standard Time'=>'Pacific/Port_Moresby',
-        'Yakutsk Standard Time'=>'Asia/Yakutsk',
-
-        // Microsoft exchange timezones
-        // Source:
-        // http://msdn.microsoft.com/en-us/library/ms988620%28v=exchg.65%29.aspx
-        //
-        // Correct timezones deduced with help from:
-        // http://en.wikipedia.org/wiki/List_of_tz_database_time_zones
-        'Universal Coordinated Time' => 'UTC',
-        'Casablanca, Monrovia' => 'Africa/Casablanca',
-        'Greenwich Mean Time: Dublin, Edinburgh, Lisbon, London' => 'Europe/Lisbon',
-        'Greenwich Mean Time; Dublin, Edinburgh, London' =>  'Europe/London',
-        'Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna' => 'Europe/Berlin',
-        'Belgrade, Pozsony, Budapest, Ljubljana, Prague' => 'Europe/Prague',
-        'Brussels, Copenhagen, Madrid, Paris' => 'Europe/Paris',
-        'Paris, Madrid, Brussels, Copenhagen' => 'Europe/Paris',
-        'Prague, Central Europe' => 'Europe/Prague',
-        'Sarajevo, Skopje, Sofija, Vilnius, Warsaw, Zagreb' => 'Europe/Sarajevo',
-        'West Central Africa' => 'Africa/Luanda', // This was a best guess
-        'Athens, Istanbul, Minsk' => 'Europe/Athens',
-        'Bucharest' => 'Europe/Bucharest',
-        'Cairo' => 'Africa/Cairo',
-        'Harare, Pretoria' => 'Africa/Harare',
-        'Helsinki, Riga, Tallinn' => 'Europe/Helsinki',
-        'Israel, Jerusalem Standard Time' => 'Asia/Jerusalem',
-        'Baghdad' => 'Asia/Baghdad',
-        'Arab, Kuwait, Riyadh' => 'Asia/Kuwait',
-        'Moscow, St. Petersburg, Volgograd' => 'Europe/Moscow',
-        'East Africa, Nairobi' => 'Africa/Nairobi',
-        'Tehran' => 'Asia/Tehran',
-        'Abu Dhabi, Muscat' => 'Asia/Muscat', // Best guess
-        'Baku, Tbilisi, Yerevan' => 'Asia/Baku',
-        'Kabul' => 'Asia/Kabul',
-        'Ekaterinburg' => 'Asia/Yekaterinburg',
-        'Islamabad, Karachi, Tashkent' => 'Asia/Karachi',
-        'Kolkata, Chennai, Mumbai, New Delhi, India Standard Time' => 'Asia/Calcutta',
-        'Kathmandu, Nepal' => 'Asia/Kathmandu',
-        'Almaty, Novosibirsk, North Central Asia' => 'Asia/Almaty',
-        'Astana, Dhaka' => 'Asia/Dhaka',
-        'Sri Jayawardenepura, Sri Lanka' => 'Asia/Colombo',
-        'Rangoon' => 'Asia/Rangoon',
-        'Bangkok, Hanoi, Jakarta' => 'Asia/Bangkok',
-        'Krasnoyarsk' => 'Asia/Krasnoyarsk',
-        'Beijing, Chongqing, Hong Kong SAR, Urumqi' => 'Asia/Shanghai',
-        'Irkutsk, Ulaan Bataar' => 'Asia/Irkutsk',
-        'Kuala Lumpur, Singapore' => 'Asia/Singapore',
-        'Perth, Western Australia' => 'Australia/Perth',
-        'Taipei' => 'Asia/Taipei',
-        'Osaka, Sapporo, Tokyo' => 'Asia/Tokyo',
-        'Seoul, Korea Standard time' => 'Asia/Seoul',
-        'Yakutsk' => 'Asia/Yakutsk',
-        'Adelaide, Central Australia' => 'Australia/Adelaide',
-        'Darwin' => 'Australia/Darwin',
-        'Brisbane, East Australia' => 'Australia/Brisbane',
-        'Canberra, Melbourne, Sydney, Hobart (year 2000 only)' => 'Australia/Sydney',
-        'Guam, Port Moresby' => 'Pacific/Guam',
-        'Hobart, Tasmania' => 'Australia/Hobart',
-        'Vladivostok' => 'Asia/Vladivostok',
-        'Magadan, Solomon Is., New Caledonia' => 'Asia/Magadan',
-        'Auckland, Wellington' => 'Pacific/Auckland',
-        'Fiji Islands, Kamchatka, Marshall Is.' => 'Pacific/Fiji',
-        'Nuku\'alofa, Tonga' => 'Pacific/Tongatapu',
-        'Azores' => 'Atlantic/Azores',
-        'Cape Verde Is.' => 'Atlantic/Cape_Verde',
-        'Mid-Atlantic' => 'America/Noronha',
-        'Brasilia' => 'America/Sao_Paulo', // Best guess
-        'Buenos Aires' => 'America/Argentina/Buenos_Aires',
-        'Greenland' => 'America/Godthab',
-        'Newfoundland' => 'America/St_Johns',
-        'Atlantic Time (Canada)' => 'America/Halifax',
-        'Caracas, La Paz' => 'America/Caracas',
-        'Santiago' => 'America/Santiago',
-        'Bogota, Lima, Quito' => 'America/Bogota',
-        'Eastern Time (US & Canada)' => 'America/New_York',
-        'Indiana (East)' => 'America/Indiana/Indianapolis',
-        'Central America' => 'America/Guatemala',
-        'Central Time (US & Canada)' => 'America/Chicago',
-        'Mexico City, Tegucigalpa' => 'America/Mexico_City',
-        'Saskatchewan' => 'America/Edmonton',
-        'Arizona' => 'America/Phoenix',
-        'Mountain Time (US & Canada)' => 'America/Denver', // Best guess
-        'Pacific Time (US & Canada); Tijuana' => 'America/Los_Angeles', // Best guess
-        'Alaska' => 'America/Anchorage',
-        'Hawaii' => 'Pacific/Honolulu',
-        'Midway Island, Samoa' => 'Pacific/Midway',
-        'Eniwetok, Kwajalein, Dateline Time' => 'Pacific/Kwajalein',
-
-        // The following list are timezone names that could be generated by
-        // Lotus / Domino
-        'Dateline'               => 'Etc/GMT-12',
-        'Samoa'                  => 'Pacific/Apia',
-        'Hawaiian'               => 'Pacific/Honolulu',
-        'Alaskan'                => 'America/Anchorage',
-        'Pacific'                => 'America/Los_Angeles',
-        'Pacific Standard Time'  => 'America/Los_Angeles',
-        'Mexico Standard Time 2' => 'America/Chihuahua',
-        'Mountain'               => 'America/Denver',
-        'Mountain Standard Time' => 'America/Chihuahua',
-        'US Mountain'            => 'America/Phoenix',
-        'Canada Central'         => 'America/Edmonton',
-        'Central America'        => 'America/Guatemala',
-        'Central'                => 'America/Chicago',
-        'Central Standard Time'  => 'America/Mexico_City',
-        'Mexico'                 => 'America/Mexico_City',
-        'Eastern'                => 'America/New_York',
-        'SA Pacific'             => 'America/Bogota',
-        'US Eastern'             => 'America/Indiana/Indianapolis',
-        'Venezuela'              => 'America/Caracas',
-        'Atlantic'               => 'America/Halifax',
-        'Central Brazilian'      => 'America/Manaus',
-        'Pacific SA'             => 'America/Santiago',
-        'SA Western'             => 'America/La_Paz',
-        'Newfoundland'           => 'America/St_Johns',
-        'Argentina'              => 'America/Argentina/Buenos_Aires',
-        'E. South America'       => 'America/Belem',
-        'Greenland'              => 'America/Godthab',
-        'Montevideo'             => 'America/Montevideo',
-        'SA Eastern'             => 'America/Belem',
-        'Mid-Atlantic'           => 'Etc/GMT-2',
-        'Azores'                 => 'Atlantic/Azores',
-        'Cape Verde'             => 'Atlantic/Cape_Verde',
-        'Greenwich'              => 'Atlantic/Reykjavik', // No I'm serious.. Greenwich is not GMT.
-        'Morocco'                => 'Africa/Casablanca',
-        'Central Europe'         => 'Europe/Prague',
-        'Central European'       => 'Europe/Sarajevo',
-        'Romance'                => 'Europe/Paris',
-        'W. Central Africa'      => 'Africa/Lagos', // Best guess
-        'W. Europe'              => 'Europe/Amsterdam',
-        'E. Europe'              => 'Europe/Minsk',
-        'Egypt'                  => 'Africa/Cairo',
-        'FLE'                    => 'Europe/Helsinki',
-        'GTB'                    => 'Europe/Athens',
-        'Israel'                 => 'Asia/Jerusalem',
-        'Jordan'                 => 'Asia/Amman',
-        'Middle East'            => 'Asia/Beirut',
-        'Namibia'                => 'Africa/Windhoek',
-        'South Africa'           => 'Africa/Harare',
-        'Arab'                   => 'Asia/Kuwait',
-        'Arabic'                 => 'Asia/Baghdad',
-        'E. Africa'              => 'Africa/Nairobi',
-        'Georgian'               => 'Asia/Tbilisi',
-        'Russian'                => 'Europe/Moscow',
-        'Iran'                   => 'Asia/Tehran',
-        'Arabian'                => 'Asia/Muscat',
-        'Armenian'               => 'Asia/Yerevan',
-        'Azerbijan'              => 'Asia/Baku',
-        'Caucasus'               => 'Asia/Yerevan',
-        'Mauritius'              => 'Indian/Mauritius',
-        'Afghanistan'            => 'Asia/Kabul',
-        'Ekaterinburg'           => 'Asia/Yekaterinburg',
-        'Pakistan'               => 'Asia/Karachi',
-        'West Asia'              => 'Asia/Tashkent',
-        'India'                  => 'Asia/Calcutta',
-        'Sri Lanka'              => 'Asia/Colombo',
-        'Nepal'                  => 'Asia/Kathmandu',
-        'Central Asia'           => 'Asia/Dhaka',
-        'N. Central Asia'        => 'Asia/Almaty',
-        'Myanmar'                => 'Asia/Rangoon',
-        'North Asia'             => 'Asia/Krasnoyarsk',
-        'SE Asia'                => 'Asia/Bangkok',
-        'China'                  => 'Asia/Shanghai',
-        'North Asia East'        => 'Asia/Irkutsk',
-        'Singapore'              => 'Asia/Singapore',
-        'Taipei'                 => 'Asia/Taipei',
-        'W. Australia'           => 'Australia/Perth',
-        'Korea'                  => 'Asia/Seoul',
-        'Tokyo'                  => 'Asia/Tokyo',
-        'Yakutsk'                => 'Asia/Yakutsk',
-        'AUS Central'            => 'Australia/Darwin',
-        'Cen. Australia'         => 'Australia/Adelaide',
-        'AUS Eastern'            => 'Australia/Sydney',
-        'E. Australia'           => 'Australia/Brisbane',
-        'Tasmania'               => 'Australia/Hobart',
-        'Vladivostok'            => 'Asia/Vladivostok',
-        'West Pacific'           => 'Pacific/Guam',
-        'Central Pacific'        => 'Asia/Magadan',
-        'Fiji'                   => 'Pacific/Fiji',
-        'New Zealand'            => 'Pacific/Auckland',
-        'Tonga'                  => 'Pacific/Tongatapu',
-
-        // PHP 5.5.10 failed on a few timezones that were valid before. We're
-        // normalizing them here.
-        'CST6CDT'   => 'America/Chicago',
-        'Cuba'      => 'America/Havana',
-        'Egypt'     => 'Africa/Cairo',
-        'Eire'      => 'Europe/Dublin',
-        'EST5EDT'   => 'America/New_York',
-        'Factory'   => 'UTC',
-        'GB-Eire'   => 'Europe/London',
-        'GMT0'      => 'UTC',
-        'Greenwich' => 'UTC',
-        'Hongkong'  => 'Asia/Hong_Kong',
-        'Iceland'   => 'Atlantic/Reykjavik',
-        'Iran'      => 'Asia/Tehran',
-        'Israel'    => 'Asia/Jerusalem',
-        'Jamaica'   => 'America/Jamaica',
-        'Japan'     => 'Asia/Tokyo',
-        'Kwajalein' => 'Pacific/Kwajalein',
-        'Libya'     => 'Africa/Tripoli',
-        'MST7MDT'   => 'America/Denver',
-        'Navajo'    => 'America/Denver',
-        'NZ-CHAT'   => 'Pacific/Chatham',
-        'Poland'    => 'Europe/Warsaw',
-        'Portugal'  => 'Europe/Lisbon',
-        'PST8PDT'   => 'America/Los_Angeles',
-        'Singapore' => 'Asia/Singapore',
-        'Turkey'    => 'Europe/Istanbul',
-        'Universal' => 'UTC',
-        'W-SU'      => 'Europe/Moscow',
-    );
-
-    /**
-     * List of microsoft exchange timezone ids.
-     *
-     * Source: http://msdn.microsoft.com/en-us/library/aa563018(loband).aspx
-     */
-    public static $microsoftExchangeMap = array(
-        0  => 'UTC',
-        31 => 'Africa/Casablanca',
-
-        // Insanely, id #2 is used for both Europe/Lisbon, and Europe/Sarajevo.
-        // I'm not even kidding.. We handle this special case in the
-        // getTimeZone method.
-        2  => 'Europe/Lisbon',
-        1  => 'Europe/London',
-        4  => 'Europe/Berlin',
-        6  => 'Europe/Prague',
-        3  => 'Europe/Paris',
-        69 => 'Africa/Luanda', // This was a best guess
-        7  => 'Europe/Athens',
-        5  => 'Europe/Bucharest',
-        49 => 'Africa/Cairo',
-        50 => 'Africa/Harare',
-        59 => 'Europe/Helsinki',
-        27 => 'Asia/Jerusalem',
-        26 => 'Asia/Baghdad',
-        74 => 'Asia/Kuwait',
-        51 => 'Europe/Moscow',
-        56 => 'Africa/Nairobi',
-        25 => 'Asia/Tehran',
-        24 => 'Asia/Muscat', // Best guess
-        54 => 'Asia/Baku',
-        48 => 'Asia/Kabul',
-        58 => 'Asia/Yekaterinburg',
-        47 => 'Asia/Karachi',
-        23 => 'Asia/Calcutta',
-        62 => 'Asia/Kathmandu',
-        46 => 'Asia/Almaty',
-        71 => 'Asia/Dhaka',
-        66 => 'Asia/Colombo',
-        61 => 'Asia/Rangoon',
-        22 => 'Asia/Bangkok',
-        64 => 'Asia/Krasnoyarsk',
-        45 => 'Asia/Shanghai',
-        63 => 'Asia/Irkutsk',
-        21 => 'Asia/Singapore',
-        73 => 'Australia/Perth',
-        75 => 'Asia/Taipei',
-        20 => 'Asia/Tokyo',
-        72 => 'Asia/Seoul',
-        70 => 'Asia/Yakutsk',
-        19 => 'Australia/Adelaide',
-        44 => 'Australia/Darwin',
-        18 => 'Australia/Brisbane',
-        76 => 'Australia/Sydney',
-        43 => 'Pacific/Guam',
-        42 => 'Australia/Hobart',
-        68 => 'Asia/Vladivostok',
-        41 => 'Asia/Magadan',
-        17 => 'Pacific/Auckland',
-        40 => 'Pacific/Fiji',
-        67 => 'Pacific/Tongatapu',
-        29 => 'Atlantic/Azores',
-        53 => 'Atlantic/Cape_Verde',
-        30 => 'America/Noronha',
-         8 => 'America/Sao_Paulo', // Best guess
-        32 => 'America/Argentina/Buenos_Aires',
-        60 => 'America/Godthab',
-        28 => 'America/St_Johns',
-         9 => 'America/Halifax',
-        33 => 'America/Caracas',
-        65 => 'America/Santiago',
-        35 => 'America/Bogota',
-        10 => 'America/New_York',
-        34 => 'America/Indiana/Indianapolis',
-        55 => 'America/Guatemala',
-        11 => 'America/Chicago',
-        37 => 'America/Mexico_City',
-        36 => 'America/Edmonton',
-        38 => 'America/Phoenix',
-        12 => 'America/Denver', // Best guess
-        13 => 'America/Los_Angeles', // Best guess
-        14 => 'America/Anchorage',
-        15 => 'Pacific/Honolulu',
-        16 => 'Pacific/Midway',
-        39 => 'Pacific/Kwajalein',
-    );
-
-    /**
-     * This method will try to find out the correct timezone for an iCalendar
-     * date-time value.
-     *
-     * You must pass the contents of the TZID parameter, as well as the full
-     * calendar.
-     *
-     * If the lookup fails, this method will return the default PHP timezone
-     * (as configured using date_default_timezone_set, or the date.timezone ini
-     * setting).
-     *
-     * Alternatively, if $failIfUncertain is set to true, it will throw an
-     * exception if we cannot accurately determine the timezone.
-     *
-     * @param string $tzid
-     * @param Sabre\VObject\Component $vcalendar
-     * @return DateTimeZone
-     */
-    static public function getTimeZone($tzid, Component $vcalendar = null, $failIfUncertain = false) {
-
-        // First we will just see if the tzid is a support timezone identifier.
-        //
-        // The only exception is if the timezone starts with (. This is to
-        // handle cases where certain microsoft products generate timezone
-        // identifiers that for instance look like:
-        //
-        // (GMT+01.00) Sarajevo/Warsaw/Zagreb
-        //
-        // Since PHP 5.5.10, the first bit will be used as the timezone and
-        // this method will return just GMT+01:00. This is wrong, because it
-        // doesn't take DST into account.
-        if ($tzid[0]!=='(') {
-            try {
-                return new \DateTimeZone($tzid);
-            } catch (\Exception $e) {
-            }
-        }
-
-        // Next, we check if the tzid is somewhere in our tzid map.
-        if (isset(self::$map[$tzid])) {
-            return new \DateTimeZone(self::$map[$tzid]);
-        }
-
-        // Maybe the author was hyper-lazy and just included an offset. We
-        // support it, but we aren't happy about it.
-        //
-        // Note that the path in the source will never be taken from PHP 5.5.10
-        // onwards. PHP 5.5.10 supports the "GMT+0100" style of format, so it
-        // already gets returned early in this function. Once we drop support
-        // for versions under PHP 5.5.10, this bit can be taken out of the
-        // source.
-        if (preg_match('/^GMT(\+|-)([0-9]{4})$/', $tzid, $matches)) {
-            return new \DateTimeZone('Etc/GMT' . $matches[1] . ltrim(substr($matches[2],0,2),'0'));
-        }
-
-        if ($vcalendar) {
-
-            // If that didn't work, we will scan VTIMEZONE objects
-            foreach($vcalendar->select('VTIMEZONE') as $vtimezone) {
-
-                if ((string)$vtimezone->TZID === $tzid) {
-
-                    // Some clients add 'X-LIC-LOCATION' with the olson name.
-                    if (isset($vtimezone->{'X-LIC-LOCATION'})) {
-
-                        $lic = (string)$vtimezone->{'X-LIC-LOCATION'};
-
-                        // Libical generators may specify strings like
-                        // "SystemV/EST5EDT". For those we must remove the
-                        // SystemV part.
-                        if (substr($lic,0,8)==='SystemV/') {
-                            $lic = substr($lic,8);
-                        }
-
-                        return self::getTimeZone($lic, null, $failIfUncertain);
-
-                    }
-                    // Microsoft may add a magic number, which we also have an
-                    // answer for.
-                    if (isset($vtimezone->{'X-MICROSOFT-CDO-TZID'})) {
-                        $cdoId = (int)$vtimezone->{'X-MICROSOFT-CDO-TZID'}->value;
-
-                        // 2 can mean both Europe/Lisbon and Europe/Sarajevo.
-                        if ($cdoId===2 && strpos((string)$vtimezone->TZID, 'Sarajevo')!==false) {
-                            return new \DateTimeZone('Europe/Sarajevo');
-                        }
-
-                        if (isset(self::$microsoftExchangeMap[$cdoId])) {
-                            return new \DateTimeZone(self::$microsoftExchangeMap[$cdoId]);
-                        }
-                    }
-
-                }
-
-            }
-
-        }
-
-        if ($failIfUncertain) {
-            throw new \InvalidArgumentException('We were unable to determine the correct PHP timezone for tzid: ' . $tzid);
-        }
-
-        // If we got all the way here, we default to UTC.
-        return new \DateTimeZone(date_default_timezone_get());
-
-    }
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Version.php b/vendor/sabre/vobject/lib/Sabre/VObject/Version.php
deleted file mode 100644
index 5b04d0b7a..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Version.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-namespace Sabre\VObject;
-
-/**
- * This class contains the version number for the VObject package
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-class Version {
-
-    /**
-     * Full version number
-     */
-    const VERSION = '2.1.4';
-
-    /**
-     * Stability : alpha, beta, stable
-     */
-    const STABILITY = 'stable';
-
-}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/includes.php b/vendor/sabre/vobject/lib/Sabre/VObject/includes.php
deleted file mode 100644
index d15329a6a..000000000
--- a/vendor/sabre/vobject/lib/Sabre/VObject/includes.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-
-/**
- * Includes file
- *
- * This file includes the entire VObject library in one go.
- * The benefit is that an autoloader is not needed, which is often faster.
- *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Evert Pot (http://evertpot.com/)
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
- */
-
-// Begin includes
-include __DIR__ . '/DateTimeParser.php';
-include __DIR__ . '/ElementList.php';
-include __DIR__ . '/FreeBusyGenerator.php';
-include __DIR__ . '/Node.php';
-include __DIR__ . '/Parameter.php';
-include __DIR__ . '/ParseException.php';
-include __DIR__ . '/Property.php';
-include __DIR__ . '/Reader.php';
-include __DIR__ . '/RecurrenceIterator.php';
-include __DIR__ . '/Splitter/SplitterInterface.php';
-include __DIR__ . '/StringUtil.php';
-include __DIR__ . '/TimeZoneUtil.php';
-include __DIR__ . '/Version.php';
-include __DIR__ . '/Splitter/VCard.php';
-include __DIR__ . '/Component.php';
-include __DIR__ . '/Document.php';
-include __DIR__ . '/Property/Compound.php';
-include __DIR__ . '/Property/DateTime.php';
-include __DIR__ . '/Property/MultiDateTime.php';
-include __DIR__ . '/Splitter/ICalendar.php';
-include __DIR__ . '/Component/VAlarm.php';
-include __DIR__ . '/Component/VCalendar.php';
-include __DIR__ . '/Component/VEvent.php';
-include __DIR__ . '/Component/VFreeBusy.php';
-include __DIR__ . '/Component/VJournal.php';
-include __DIR__ . '/Component/VTodo.php';
-// End includes
diff --git a/vendor/sabre/vobject/lib/Settings.php b/vendor/sabre/vobject/lib/Settings.php
new file mode 100644
index 000000000..3f274ba8e
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Settings.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * This class provides a list of global defaults for vobject.
+ *
+ * Some of these started to appear in various classes, so it made a bit more
+ * sense to centralize them, so it's easier for user to find and change these.
+ *
+ * The global nature of them does mean that changing the settings for one
+ * instance has a global influence.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Settings {
+
+    /**
+     * The minimum date we accept for various calculations with dates, such as
+     * recurrences.
+     *
+     * The choice of 1900 is pretty arbitrary, but it covers most common
+     * use-cases. In particular, it covers birthdates for virtually everyone
+     * alive on earth, which is less than 5 people at the time of writing.
+     */
+    static $minDate = '1900-01-01';
+
+    /**
+     * The maximum date we accept for various calculations with dates, such as
+     * recurrences.
+     *
+     * The choice of 2100 is pretty arbitrary, but should cover most
+     * appointments made for many years to come.
+     */
+    static $maxDate = '2100-01-01';
+
+    /**
+     * The maximum number of recurrences that will be generated.
+     *
+     * This setting limits the maximum of recurring events that this library
+     * generates in its recurrence iterators.
+     *
+     * This is a security measure. Without this, it would be possible to craft
+     * specific events that recur many, many times, potentially DDOSing the
+     * server.
+     *
+     * The default (3500) allows creation of a dialy event that goes on for 10
+     * years, which is hopefully long enough for most.
+     *
+     * Set this value to -1 to disable this control altogether.
+     */
+    static $maxRecurrences = 3500;
+
+}
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Splitter/ICalendar.php b/vendor/sabre/vobject/lib/Splitter/ICalendar.php
index 657cfb810..c0007ba01 100644
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Splitter/ICalendar.php
+++ b/vendor/sabre/vobject/lib/Splitter/ICalendar.php
@@ -3,9 +3,10 @@
 namespace Sabre\VObject\Splitter;
 
 use Sabre\VObject;
+use Sabre\VObject\Component\VCalendar;
 
 /**
- * Splitter
+ * Splitter.
  *
  * This class is responsible for splitting up iCalendar objects.
  *
@@ -13,41 +14,44 @@ use Sabre\VObject;
  * calendar-objects inside. Objects with identical UID's will be combined into
  * a single object.
  *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Dominik Tobschall
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Dominik Tobschall (http://tobschall.de/)
  * @author Armin Hackmann
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ * @license http://sabre.io/license/ Modified BSD License
  */
 class ICalendar implements SplitterInterface {
 
     /**
-     * Timezones
+     * Timezones.
      *
      * @var array
      */
-    protected $vtimezones = array();
+    protected $vtimezones = [];
 
     /**
-     * iCalendar objects
+     * iCalendar objects.
      *
      * @var array
      */
-    protected $objects = array();
+    protected $objects = [];
 
     /**
-     * Constructor
+     * Constructor.
      *
      * The splitter should receive an readable file stream as it's input.
      *
      * @param resource $input
+     * @param int $options Parser options, see the OPTIONS constants.
      */
-    public function __construct($input) {
+    function __construct($input, $options = 0) {
 
-        $data = VObject\Reader::read(stream_get_contents($input));
-        $vtimezones = array();
-        $components = array();
+        $data = VObject\Reader::read($input, $options);
 
-        foreach($data->children as $component) {
+        if (!$data instanceof VObject\Component\VCalendar) {
+            throw new VObject\ParseException('Supplied input could not be parsed as VCALENDAR.');
+        }
+
+        foreach ($data->children() as $component) {
             if (!$component instanceof VObject\Component) {
                 continue;
             }
@@ -59,16 +63,14 @@ class ICalendar implements SplitterInterface {
             }
 
             // Get component UID for recurring Events search
-            if($component->UID) {
-                $uid = (string)$component->UID;
-            } else {
-                // Generating a random UID
-                $uid = sha1(microtime()) . '-vobjectimport';
+            if (!$component->UID) {
+                $component->UID = sha1(microtime()) . '-vobjectimport';
             }
+            $uid = (string)$component->UID;
 
             // Take care of recurring events
             if (!array_key_exists($uid, $this->objects)) {
-                $this->objects[$uid] = VObject\Component::create('VCALENDAR');
+                $this->objects[$uid] = new VCalendar();
             }
 
             $this->objects[$uid]->add(clone $component);
@@ -84,9 +86,9 @@ class ICalendar implements SplitterInterface {
      *
      * @return Sabre\VObject\Component|null
      */
-    public function getNext() {
+    function getNext() {
 
-        if($object=array_shift($this->objects)) {
+        if ($object = array_shift($this->objects)) {
 
             // create our baseobject
             $object->version = '2.0';
@@ -102,10 +104,10 @@ class ICalendar implements SplitterInterface {
 
         } else {
 
-            return null;
+            return;
 
         }
 
-   }
+    }
 
 }
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Splitter/SplitterInterface.php b/vendor/sabre/vobject/lib/Splitter/SplitterInterface.php
index c0126883a..8f827cc4b 100644
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Splitter/SplitterInterface.php
+++ b/vendor/sabre/vobject/lib/Splitter/SplitterInterface.php
@@ -3,7 +3,7 @@
 namespace Sabre\VObject\Splitter;
 
 /**
- * VObject splitter
+ * VObject splitter.
  *
  * The splitter is responsible for reading a large vCard or iCalendar object,
  * and splitting it into multiple objects.
@@ -11,14 +11,14 @@ namespace Sabre\VObject\Splitter;
  * This is for example for Card and CalDAV, which require every event and vcard
  * to exist in their own objects, instead of one large one.
  *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Dominik Tobschall
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Dominik Tobschall (http://tobschall.de/)
+ * @license http://sabre.io/license/ Modified BSD License
  */
 interface SplitterInterface {
 
     /**
-     * Constructor
+     * Constructor.
      *
      * The splitter should receive an readable file stream as it's input.
      *
diff --git a/vendor/sabre/vobject/lib/Sabre/VObject/Splitter/VCard.php b/vendor/sabre/vobject/lib/Splitter/VCard.php
index 7a8718c00..0bb82abe9 100644
--- a/vendor/sabre/vobject/lib/Sabre/VObject/Splitter/VCard.php
+++ b/vendor/sabre/vobject/lib/Splitter/VCard.php
@@ -3,9 +3,10 @@
 namespace Sabre\VObject\Splitter;
 
 use Sabre\VObject;
+use Sabre\VObject\Parser\MimeDir;
 
 /**
- * Splitter
+ * Splitter.
  *
  * This class is responsible for splitting up VCard objects.
  *
@@ -13,30 +14,39 @@ use Sabre\VObject;
  * class checks for BEGIN:VCARD and END:VCARD and parses each encountered
  * component individually.
  *
- * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
- * @author Dominik Tobschall
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Dominik Tobschall (http://tobschall.de/)
  * @author Armin Hackmann
- * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ * @license http://sabre.io/license/ Modified BSD License
  */
 class VCard implements SplitterInterface {
 
     /**
-     * File handle
+     * File handle.
      *
      * @var resource
      */
     protected $input;
 
     /**
-     * Constructor
+     * Persistent parser.
+     *
+     * @var MimeDir
+     */
+    protected $parser;
+
+    /**
+     * Constructor.
      *
      * The splitter should receive an readable file stream as it's input.
      *
      * @param resource $input
+     * @param int $options Parser options, see the OPTIONS constants.
      */
-    public function __construct($input) {
+    function __construct($input, $options = 0) {
 
         $this->input = $input;
+        $this->parser = new MimeDir($input, $options);
 
     }
 
@@ -48,25 +58,17 @@ class VCard implements SplitterInterface {
      *
      * @return Sabre\VObject\Component|null
      */
-    public function getNext() {
+    function getNext() {
 
-        $vcard = '';
+        try {
+            $object = $this->parser->parse();
 
-        do {
-
-            if (feof($this->input)) {
-                return false;
+            if (!$object instanceof VObject\Component\VCard) {
+                throw new VObject\ParseException('The supplied input contained non-VCARD data.');
             }
 
-            $line = fgets($this->input);
-            $vcard .= $line;
-
-        } while(strtoupper(substr($line,0,4))!=="END:");
-
-        $object = VObject\Reader::read($vcard);
-
-        if($object->name !== 'VCARD') {
-            throw new \InvalidArgumentException("Thats no vCard!", 1);
+        } catch (VObject\EofException $e) {
+            return;
         }
 
         return $object;
diff --git a/vendor/sabre/vobject/lib/StringUtil.php b/vendor/sabre/vobject/lib/StringUtil.php
new file mode 100644
index 000000000..b8615f2ba
--- /dev/null
+++ b/vendor/sabre/vobject/lib/StringUtil.php
@@ -0,0 +1,66 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * Useful utilities for working with various strings.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class StringUtil {
+
+    /**
+     * Returns true or false depending on if a string is valid UTF-8.
+     *
+     * @param string $str
+     *
+     * @return bool
+     */
+    static function isUTF8($str) {
+
+        // Control characters
+        if (preg_match('%[\x00-\x08\x0B-\x0C\x0E\x0F]%', $str)) {
+            return false;
+        }
+
+        return (bool)preg_match('%%u', $str);
+
+    }
+
+    /**
+     * This method tries its best to convert the input string to UTF-8.
+     *
+     * Currently only ISO-5991-1 input and UTF-8 input is supported, but this
+     * may be expanded upon if we receive other examples.
+     *
+     * @param string $str
+     *
+     * @return string
+     */
+    static function convertToUTF8($str) {
+
+        $encoding = mb_detect_encoding($str, ['UTF-8', 'ISO-8859-1', 'WINDOWS-1252'], true);
+
+        switch ($encoding) {
+            case 'ISO-8859-1' :
+                $newStr = utf8_encode($str);
+                break;
+            /* Unreachable code. Not sure yet how we can improve this
+             * situation.
+            case 'WINDOWS-1252' :
+                $newStr = iconv('cp1252', 'UTF-8', $str);
+                break;
+             */
+            default :
+                 $newStr = $str;
+
+        }
+
+        // Removing any control characters
+        return (preg_replace('%(?:[\x00-\x08\x0B-\x0C\x0E-\x1F\x7F])%', '', $newStr));
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/TimeZoneUtil.php b/vendor/sabre/vobject/lib/TimeZoneUtil.php
new file mode 100644
index 000000000..4873daf92
--- /dev/null
+++ b/vendor/sabre/vobject/lib/TimeZoneUtil.php
@@ -0,0 +1,266 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * Time zone name translation.
+ *
+ * This file translates well-known time zone names into "Olson database" time zone names.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Frank Edelhaeuser (fedel@users.sourceforge.net)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class TimeZoneUtil {
+
+    static $map = null;
+
+    /**
+     * List of microsoft exchange timezone ids.
+     *
+     * Source: http://msdn.microsoft.com/en-us/library/aa563018(loband).aspx
+     */
+    static $microsoftExchangeMap = [
+        0  => 'UTC',
+        31 => 'Africa/Casablanca',
+
+        // Insanely, id #2 is used for both Europe/Lisbon, and Europe/Sarajevo.
+        // I'm not even kidding.. We handle this special case in the
+        // getTimeZone method.
+        2  => 'Europe/Lisbon',
+        1  => 'Europe/London',
+        4  => 'Europe/Berlin',
+        6  => 'Europe/Prague',
+        3  => 'Europe/Paris',
+        69 => 'Africa/Luanda', // This was a best guess
+        7  => 'Europe/Athens',
+        5  => 'Europe/Bucharest',
+        49 => 'Africa/Cairo',
+        50 => 'Africa/Harare',
+        59 => 'Europe/Helsinki',
+        27 => 'Asia/Jerusalem',
+        26 => 'Asia/Baghdad',
+        74 => 'Asia/Kuwait',
+        51 => 'Europe/Moscow',
+        56 => 'Africa/Nairobi',
+        25 => 'Asia/Tehran',
+        24 => 'Asia/Muscat', // Best guess
+        54 => 'Asia/Baku',
+        48 => 'Asia/Kabul',
+        58 => 'Asia/Yekaterinburg',
+        47 => 'Asia/Karachi',
+        23 => 'Asia/Calcutta',
+        62 => 'Asia/Kathmandu',
+        46 => 'Asia/Almaty',
+        71 => 'Asia/Dhaka',
+        66 => 'Asia/Colombo',
+        61 => 'Asia/Rangoon',
+        22 => 'Asia/Bangkok',
+        64 => 'Asia/Krasnoyarsk',
+        45 => 'Asia/Shanghai',
+        63 => 'Asia/Irkutsk',
+        21 => 'Asia/Singapore',
+        73 => 'Australia/Perth',
+        75 => 'Asia/Taipei',
+        20 => 'Asia/Tokyo',
+        72 => 'Asia/Seoul',
+        70 => 'Asia/Yakutsk',
+        19 => 'Australia/Adelaide',
+        44 => 'Australia/Darwin',
+        18 => 'Australia/Brisbane',
+        76 => 'Australia/Sydney',
+        43 => 'Pacific/Guam',
+        42 => 'Australia/Hobart',
+        68 => 'Asia/Vladivostok',
+        41 => 'Asia/Magadan',
+        17 => 'Pacific/Auckland',
+        40 => 'Pacific/Fiji',
+        67 => 'Pacific/Tongatapu',
+        29 => 'Atlantic/Azores',
+        53 => 'Atlantic/Cape_Verde',
+        30 => 'America/Noronha',
+         8 => 'America/Sao_Paulo', // Best guess
+        32 => 'America/Argentina/Buenos_Aires',
+        60 => 'America/Godthab',
+        28 => 'America/St_Johns',
+         9 => 'America/Halifax',
+        33 => 'America/Caracas',
+        65 => 'America/Santiago',
+        35 => 'America/Bogota',
+        10 => 'America/New_York',
+        34 => 'America/Indiana/Indianapolis',
+        55 => 'America/Guatemala',
+        11 => 'America/Chicago',
+        37 => 'America/Mexico_City',
+        36 => 'America/Edmonton',
+        38 => 'America/Phoenix',
+        12 => 'America/Denver', // Best guess
+        13 => 'America/Los_Angeles', // Best guess
+        14 => 'America/Anchorage',
+        15 => 'Pacific/Honolulu',
+        16 => 'Pacific/Midway',
+        39 => 'Pacific/Kwajalein',
+    ];
+
+    /**
+     * This method will try to find out the correct timezone for an iCalendar
+     * date-time value.
+     *
+     * You must pass the contents of the TZID parameter, as well as the full
+     * calendar.
+     *
+     * If the lookup fails, this method will return the default PHP timezone
+     * (as configured using date_default_timezone_set, or the date.timezone ini
+     * setting).
+     *
+     * Alternatively, if $failIfUncertain is set to true, it will throw an
+     * exception if we cannot accurately determine the timezone.
+     *
+     * @param string $tzid
+     * @param Sabre\VObject\Component $vcalendar
+     *
+     * @return DateTimeZone
+     */
+    static function getTimeZone($tzid, Component $vcalendar = null, $failIfUncertain = false) {
+
+        // First we will just see if the tzid is a support timezone identifier.
+        //
+        // The only exception is if the timezone starts with (. This is to
+        // handle cases where certain microsoft products generate timezone
+        // identifiers that for instance look like:
+        //
+        // (GMT+01.00) Sarajevo/Warsaw/Zagreb
+        //
+        // Since PHP 5.5.10, the first bit will be used as the timezone and
+        // this method will return just GMT+01:00. This is wrong, because it
+        // doesn't take DST into account.
+        if ($tzid[0] !== '(') {
+
+            // PHP has a bug that logs PHP warnings even it shouldn't:
+            // https://bugs.php.net/bug.php?id=67881
+            //
+            // That's why we're checking if we'll be able to successfull instantiate
+            // \DateTimeZone() before doing so. Otherwise we could simply instantiate
+            // and catch the exception.
+            $tzIdentifiers = \DateTimeZone::listIdentifiers();
+
+            try {
+                if (
+                    (in_array($tzid, $tzIdentifiers)) ||
+                    (preg_match('/^GMT(\+|-)([0-9]{4})$/', $tzid, $matches)) ||
+                    (in_array($tzid, self::getIdentifiersBC()))
+                ) {
+                    return new \DateTimeZone($tzid);
+                }
+            } catch (\Exception $e) {
+            }
+
+        }
+
+        self::loadTzMaps();
+
+        // Next, we check if the tzid is somewhere in our tzid map.
+        if (isset(self::$map[$tzid])) {
+            return new \DateTimeZone(self::$map[$tzid]);
+        }
+
+        // Maybe the author was hyper-lazy and just included an offset. We
+        // support it, but we aren't happy about it.
+        if (preg_match('/^GMT(\+|-)([0-9]{4})$/', $tzid, $matches)) {
+
+            // Note that the path in the source will never be taken from PHP 5.5.10
+            // onwards. PHP 5.5.10 supports the "GMT+0100" style of format, so it
+            // already gets returned early in this function. Once we drop support
+            // for versions under PHP 5.5.10, this bit can be taken out of the
+            // source.
+            // @codeCoverageIgnoreStart
+            return new \DateTimeZone('Etc/GMT' . $matches[1] . ltrim(substr($matches[2], 0, 2), '0'));
+            // @codeCoverageIgnoreEnd
+        }
+
+        if ($vcalendar) {
+
+            // If that didn't work, we will scan VTIMEZONE objects
+            foreach ($vcalendar->select('VTIMEZONE') as $vtimezone) {
+
+                if ((string)$vtimezone->TZID === $tzid) {
+
+                    // Some clients add 'X-LIC-LOCATION' with the olson name.
+                    if (isset($vtimezone->{'X-LIC-LOCATION'})) {
+
+                        $lic = (string)$vtimezone->{'X-LIC-LOCATION'};
+
+                        // Libical generators may specify strings like
+                        // "SystemV/EST5EDT". For those we must remove the
+                        // SystemV part.
+                        if (substr($lic, 0, 8) === 'SystemV/') {
+                            $lic = substr($lic, 8);
+                        }
+
+                        return self::getTimeZone($lic, null, $failIfUncertain);
+
+                    }
+                    // Microsoft may add a magic number, which we also have an
+                    // answer for.
+                    if (isset($vtimezone->{'X-MICROSOFT-CDO-TZID'})) {
+                        $cdoId = (int)$vtimezone->{'X-MICROSOFT-CDO-TZID'}->getValue();
+
+                        // 2 can mean both Europe/Lisbon and Europe/Sarajevo.
+                        if ($cdoId === 2 && strpos((string)$vtimezone->TZID, 'Sarajevo') !== false) {
+                            return new \DateTimeZone('Europe/Sarajevo');
+                        }
+
+                        if (isset(self::$microsoftExchangeMap[$cdoId])) {
+                            return new \DateTimeZone(self::$microsoftExchangeMap[$cdoId]);
+                        }
+                    }
+
+                }
+
+            }
+
+        }
+
+        if ($failIfUncertain) {
+            throw new \InvalidArgumentException('We were unable to determine the correct PHP timezone for tzid: ' . $tzid);
+        }
+
+        // If we got all the way here, we default to UTC.
+        return new \DateTimeZone(date_default_timezone_get());
+
+    }
+
+    /**
+     * This method will load in all the tz mapping information, if it's not yet
+     * done.
+     */
+    static function loadTzMaps() {
+
+        if (!is_null(self::$map)) return;
+
+        self::$map = array_merge(
+            include __DIR__ .  '/timezonedata/windowszones.php',
+            include __DIR__ .  '/timezonedata/lotuszones.php',
+            include __DIR__ .  '/timezonedata/exchangezones.php',
+            include __DIR__ .  '/timezonedata/php-workaround.php'
+        );
+
+    }
+
+    /**
+     * This method returns an array of timezone identifiers, that are supported
+     * by DateTimeZone(), but not returned by DateTimeZone::listIdentifiers().
+     *
+     * We're not using DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC) because:
+     * - It's not supported by some PHP versions as well as HHVM.
+     * - It also returns identifiers, that are invalid values for new DateTimeZone() on some PHP versions.
+     * (See timezonedata/php-bc.php and timezonedata php-workaround.php)
+     *
+     * @return array
+     */
+    static function getIdentifiersBC() {
+        return include __DIR__ .  '/timezonedata/php-bc.php';
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/UUIDUtil.php b/vendor/sabre/vobject/lib/UUIDUtil.php
new file mode 100644
index 000000000..24ebe3cf8
--- /dev/null
+++ b/vendor/sabre/vobject/lib/UUIDUtil.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * UUID Utility.
+ *
+ * This class has static methods to generate and validate UUID's.
+ * UUIDs are used a decent amount within various *DAV standards, so it made
+ * sense to include it.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class UUIDUtil {
+
+    /**
+     * Returns a pseudo-random v4 UUID.
+     *
+     * This function is based on a comment by Andrew Moore on php.net
+     *
+     * @see http://www.php.net/manual/en/function.uniqid.php#94959
+     *
+     * @return string
+     */
+    static function getUUID() {
+
+        return sprintf(
+
+            '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
+
+            // 32 bits for "time_low"
+            mt_rand(0, 0xffff), mt_rand(0, 0xffff),
+
+            // 16 bits for "time_mid"
+            mt_rand(0, 0xffff),
+
+            // 16 bits for "time_hi_and_version",
+            // four most significant bits holds version number 4
+            mt_rand(0, 0x0fff) | 0x4000,
+
+            // 16 bits, 8 bits for "clk_seq_hi_res",
+            // 8 bits for "clk_seq_low",
+            // two most significant bits holds zero and one for variant DCE1.1
+            mt_rand(0, 0x3fff) | 0x8000,
+
+            // 48 bits for "node"
+            mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
+        );
+    }
+
+    /**
+     * Checks if a string is a valid UUID.
+     *
+     * @param string $uuid
+     *
+     * @return bool
+     */
+    static function validateUUID($uuid) {
+
+        return preg_match(
+            '/^[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$/i',
+            $uuid
+        ) !== 0;
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/VCardConverter.php b/vendor/sabre/vobject/lib/VCardConverter.php
new file mode 100644
index 000000000..1f6d016f1
--- /dev/null
+++ b/vendor/sabre/vobject/lib/VCardConverter.php
@@ -0,0 +1,467 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * This utility converts vcards from one version to another.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class VCardConverter {
+
+    /**
+     * Converts a vCard object to a new version.
+     *
+     * targetVersion must be one of:
+     *   Document::VCARD21
+     *   Document::VCARD30
+     *   Document::VCARD40
+     *
+     * Currently only 3.0 and 4.0 as input and output versions.
+     *
+     * 2.1 has some minor support for the input version, it's incomplete at the
+     * moment though.
+     *
+     * If input and output version are identical, a clone is returned.
+     *
+     * @param Component\VCard $input
+     * @param int $targetVersion
+     */
+    function convert(Component\VCard $input, $targetVersion) {
+
+        $inputVersion = $input->getDocumentType();
+        if ($inputVersion === $targetVersion) {
+            return clone $input;
+        }
+
+        if (!in_array($inputVersion, [Document::VCARD21, Document::VCARD30, Document::VCARD40])) {
+            throw new \InvalidArgumentException('Only vCard 2.1, 3.0 and 4.0 are supported for the input data');
+        }
+        if (!in_array($targetVersion, [Document::VCARD30, Document::VCARD40])) {
+            throw new \InvalidArgumentException('You can only use vCard 3.0 or 4.0 for the target version');
+        }
+
+        $newVersion = $targetVersion === Document::VCARD40 ? '4.0' : '3.0';
+
+        $output = new Component\VCard([
+            'VERSION' => $newVersion,
+        ]);
+
+        // We might have generated a default UID. Remove it!
+        unset($output->UID);
+
+        foreach ($input->children() as $property) {
+
+            $this->convertProperty($input, $output, $property, $targetVersion);
+
+        }
+
+        return $output;
+
+    }
+
+    /**
+     * Handles conversion of a single property.
+     *
+     * @param Component\VCard $input
+     * @param Component\VCard $output
+     * @param Property $property
+     * @param int $targetVersion
+     *
+     * @return void
+     */
+    protected function convertProperty(Component\VCard $input, Component\VCard $output, Property $property, $targetVersion) {
+
+        // Skipping these, those are automatically added.
+        if (in_array($property->name, ['VERSION', 'PRODID'])) {
+            return;
+        }
+
+        $parameters = $property->parameters();
+        $valueType = null;
+        if (isset($parameters['VALUE'])) {
+            $valueType = $parameters['VALUE']->getValue();
+            unset($parameters['VALUE']);
+        }
+        if (!$valueType) {
+            $valueType = $property->getValueType();
+        }
+        $newProperty = $output->createProperty(
+            $property->name,
+            $property->getParts(),
+            [], // parameters will get added a bit later.
+            $valueType
+        );
+
+
+        if ($targetVersion === Document::VCARD30) {
+
+            if ($property instanceof Property\Uri && in_array($property->name, ['PHOTO', 'LOGO', 'SOUND'])) {
+
+                $newProperty = $this->convertUriToBinary($output, $newProperty);
+
+            } elseif ($property instanceof Property\VCard\DateAndOrTime) {
+
+                // In vCard 4, the birth year may be optional. This is not the
+                // case for vCard 3. Apple has a workaround for this that
+                // allows applications that support Apple's extension still
+                // omit birthyears in vCard 3, but applications that do not
+                // support this, will just use a random birthyear. We're
+                // choosing 1604 for the birthyear, because that's what apple
+                // uses.
+                $parts = DateTimeParser::parseVCardDateTime($property->getValue());
+                if (is_null($parts['year'])) {
+                    $newValue = '1604-' . $parts['month'] . '-' . $parts['date'];
+                    $newProperty->setValue($newValue);
+                    $newProperty['X-APPLE-OMIT-YEAR'] = '1604';
+                }
+
+                if ($newProperty->name == 'ANNIVERSARY') {
+                    // Microsoft non-standard anniversary
+                    $newProperty->name = 'X-ANNIVERSARY';
+
+                    // We also need to add a new apple property for the same
+                    // purpose. This apple property needs a 'label' in the same
+                    // group, so we first need to find a groupname that doesn't
+                    // exist yet.
+                    $x = 1;
+                    while ($output->select('ITEM' . $x . '.')) {
+                        $x++;
+                    }
+                    $output->add('ITEM' . $x . '.X-ABDATE', $newProperty->getValue(), ['VALUE' => 'DATE-AND-OR-TIME']);
+                    $output->add('ITEM' . $x . '.X-ABLABEL', '_$!<Anniversary>!$_');
+                }
+
+            } elseif ($property->name === 'KIND') {
+
+                switch (strtolower($property->getValue())) {
+                    case 'org' :
+                        // vCard 3.0 does not have an equivalent to KIND:ORG,
+                        // but apple has an extension that means the same
+                        // thing.
+                        $newProperty = $output->createProperty('X-ABSHOWAS', 'COMPANY');
+                        break;
+
+                    case 'individual' :
+                        // Individual is implicit, so we skip it.
+                        return;
+
+                    case 'group' :
+                        // OS X addressbook property
+                        $newProperty = $output->createProperty('X-ADDRESSBOOKSERVER-KIND', 'GROUP');
+                        break;
+                }
+
+
+            }
+
+        } elseif ($targetVersion === Document::VCARD40) {
+
+            // These properties were removed in vCard 4.0
+            if (in_array($property->name, ['NAME', 'MAILER', 'LABEL', 'CLASS'])) {
+                return;
+            }
+
+            if ($property instanceof Property\Binary) {
+
+                $newProperty = $this->convertBinaryToUri($output, $newProperty, $parameters);
+
+            } elseif ($property instanceof Property\VCard\DateAndOrTime && isset($parameters['X-APPLE-OMIT-YEAR'])) {
+
+                // If a property such as BDAY contained 'X-APPLE-OMIT-YEAR',
+                // then we're stripping the year from the vcard 4 value.
+                $parts = DateTimeParser::parseVCardDateTime($property->getValue());
+                if ($parts['year'] === $property['X-APPLE-OMIT-YEAR']->getValue()) {
+                    $newValue = '--' . $parts['month'] . '-' . $parts['date'];
+                    $newProperty->setValue($newValue);
+                }
+
+                // Regardless if the year matched or not, we do need to strip
+                // X-APPLE-OMIT-YEAR.
+                unset($parameters['X-APPLE-OMIT-YEAR']);
+
+            }
+            switch ($property->name) {
+                case 'X-ABSHOWAS' :
+                    if (strtoupper($property->getValue()) === 'COMPANY') {
+                        $newProperty = $output->createProperty('KIND', 'ORG');
+                    }
+                    break;
+                case 'X-ADDRESSBOOKSERVER-KIND' :
+                    if (strtoupper($property->getValue()) === 'GROUP') {
+                        $newProperty = $output->createProperty('KIND', 'GROUP');
+                    }
+                    break;
+                case 'X-ANNIVERSARY' :
+                    $newProperty->name = 'ANNIVERSARY';
+                    // If we already have an anniversary property with the same
+                    // value, ignore.
+                    foreach ($output->select('ANNIVERSARY') as $anniversary) {
+                        if ($anniversary->getValue() === $newProperty->getValue()) {
+                            return;
+                        }
+                    }
+                    break;
+                case 'X-ABDATE' :
+                    // Find out what the label was, if it exists.
+                    if (!$property->group) {
+                        break;
+                    }
+                    $label = $input->{$property->group . '.X-ABLABEL'};
+
+                    // We only support converting anniversaries.
+                    if (!$label || $label->getValue() !== '_$!<Anniversary>!$_') {
+                        break;
+                    }
+
+                    // If we already have an anniversary property with the same
+                    // value, ignore.
+                    foreach ($output->select('ANNIVERSARY') as $anniversary) {
+                        if ($anniversary->getValue() === $newProperty->getValue()) {
+                            return;
+                        }
+                    }
+                    $newProperty->name = 'ANNIVERSARY';
+                    break;
+                // Apple's per-property label system.
+                case 'X-ABLABEL' :
+                    if ($newProperty->getValue() === '_$!<Anniversary>!$_') {
+                        // We can safely remove these, as they are converted to
+                        // ANNIVERSARY properties.
+                        return;
+                    }
+                    break;
+
+            }
+
+        }
+
+        // set property group
+        $newProperty->group = $property->group;
+
+        if ($targetVersion === Document::VCARD40) {
+            $this->convertParameters40($newProperty, $parameters);
+        } else {
+            $this->convertParameters30($newProperty, $parameters);
+        }
+
+        // Lastly, we need to see if there's a need for a VALUE parameter.
+        //
+        // We can do that by instantating a empty property with that name, and
+        // seeing if the default valueType is identical to the current one.
+        $tempProperty = $output->createProperty($newProperty->name);
+        if ($tempProperty->getValueType() !== $newProperty->getValueType()) {
+            $newProperty['VALUE'] = $newProperty->getValueType();
+        }
+
+        $output->add($newProperty);
+
+
+    }
+
+    /**
+     * Converts a BINARY property to a URI property.
+     *
+     * vCard 4.0 no longer supports BINARY properties.
+     *
+     * @param Component\VCard $output
+     * @param Property\Uri $property The input property.
+     * @param $parameters List of parameters that will eventually be added to
+     *                    the new property.
+     *
+     * @return Property\Uri
+     */
+    protected function convertBinaryToUri(Component\VCard $output, Property\Binary $newProperty, array &$parameters) {
+
+        $value = $newProperty->getValue();
+        $newProperty = $output->createProperty(
+            $newProperty->name,
+            null, // no value
+            [], // no parameters yet
+            'URI' // Forcing the BINARY type
+        );
+
+        $mimeType = 'application/octet-stream';
+
+        // See if we can find a better mimetype.
+        if (isset($parameters['TYPE'])) {
+
+            $newTypes = [];
+            foreach ($parameters['TYPE']->getParts() as $typePart) {
+                if (in_array(
+                    strtoupper($typePart),
+                    ['JPEG', 'PNG', 'GIF']
+                )) {
+                    $mimeType = 'image/' . strtolower($typePart);
+                } else {
+                    $newTypes[] = $typePart;
+                }
+            }
+
+            // If there were any parameters we're not converting to a
+            // mime-type, we need to keep them.
+            if ($newTypes) {
+                $parameters['TYPE']->setParts($newTypes);
+            } else {
+                unset($parameters['TYPE']);
+            }
+
+        }
+
+        $newProperty->setValue('data:' . $mimeType . ';base64,' . base64_encode($value));
+        return $newProperty;
+
+    }
+
+    /**
+     * Converts a URI property to a BINARY property.
+     *
+     * In vCard 4.0 attachments are encoded as data: uri. Even though these may
+     * be valid in vCard 3.0 as well, we should convert those to BINARY if
+     * possible, to improve compatibility.
+     *
+     * @param Component\VCard $output
+     * @param Property\Uri $property The input property.
+     *
+     * @return Property\Binary|null
+     */
+    protected function convertUriToBinary(Component\VCard $output, Property\Uri $newProperty) {
+
+        $value = $newProperty->getValue();
+
+        // Only converting data: uris
+        if (substr($value, 0, 5) !== 'data:') {
+            return $newProperty;
+        }
+
+        $newProperty = $output->createProperty(
+            $newProperty->name,
+            null, // no value
+            [], // no parameters yet
+            'BINARY'
+        );
+
+        $mimeType = substr($value, 5, strpos($value, ',') - 5);
+        if (strpos($mimeType, ';')) {
+            $mimeType = substr($mimeType, 0, strpos($mimeType, ';'));
+            $newProperty->setValue(base64_decode(substr($value, strpos($value, ',') + 1)));
+        } else {
+            $newProperty->setValue(substr($value, strpos($value, ',') + 1));
+        }
+        unset($value);
+
+        $newProperty['ENCODING'] = 'b';
+        switch ($mimeType) {
+
+            case 'image/jpeg' :
+                $newProperty['TYPE'] = 'JPEG';
+                break;
+            case 'image/png' :
+                $newProperty['TYPE'] = 'PNG';
+                break;
+            case 'image/gif' :
+                $newProperty['TYPE'] = 'GIF';
+                break;
+
+        }
+
+
+        return $newProperty;
+
+    }
+
+    /**
+     * Adds parameters to a new property for vCard 4.0.
+     *
+     * @param Property $newProperty
+     * @param array $parameters
+     *
+     * @return void
+     */
+    protected function convertParameters40(Property $newProperty, array $parameters) {
+
+        // Adding all parameters.
+        foreach ($parameters as $param) {
+
+            // vCard 2.1 allowed parameters with no name
+            if ($param->noName) $param->noName = false;
+
+            switch ($param->name) {
+
+                // We need to see if there's any TYPE=PREF, because in vCard 4
+                // that's now PREF=1.
+                case 'TYPE' :
+                    foreach ($param->getParts() as $paramPart) {
+
+                        if (strtoupper($paramPart) === 'PREF') {
+                            $newProperty->add('PREF', '1');
+                        } else {
+                            $newProperty->add($param->name, $paramPart);
+                        }
+
+                    }
+                    break;
+                // These no longer exist in vCard 4
+                case 'ENCODING' :
+                case 'CHARSET' :
+                    break;
+
+                default :
+                    $newProperty->add($param->name, $param->getParts());
+                    break;
+
+            }
+
+        }
+
+    }
+
+    /**
+     * Adds parameters to a new property for vCard 3.0.
+     *
+     * @param Property $newProperty
+     * @param array $parameters
+     *
+     * @return void
+     */
+    protected function convertParameters30(Property $newProperty, array $parameters) {
+
+        // Adding all parameters.
+        foreach ($parameters as $param) {
+
+            // vCard 2.1 allowed parameters with no name
+            if ($param->noName) $param->noName = false;
+
+            switch ($param->name) {
+
+                case 'ENCODING' :
+                    // This value only existed in vCard 2.1, and should be
+                    // removed for anything else.
+                    if (strtoupper($param->getValue()) !== 'QUOTED-PRINTABLE') {
+                        $newProperty->add($param->name, $param->getParts());
+                    }
+                    break;
+
+                /*
+                 * Converting PREF=1 to TYPE=PREF.
+                 *
+                 * Any other PREF numbers we'll drop.
+                 */
+                case 'PREF' :
+                    if ($param->getValue() == '1') {
+                        $newProperty->add('TYPE', 'PREF');
+                    }
+                    break;
+
+                default :
+                    $newProperty->add($param->name, $param->getParts());
+                    break;
+
+            }
+
+        }
+
+    }
+}
diff --git a/vendor/sabre/vobject/lib/Version.php b/vendor/sabre/vobject/lib/Version.php
new file mode 100644
index 000000000..0b0e16c03
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Version.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Sabre\VObject;
+
+/**
+ * This class contains the version number for the VObject package.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Version {
+
+    /**
+     * Full version number.
+     */
+    const VERSION = '4.1.0';
+
+}
diff --git a/vendor/sabre/vobject/lib/Writer.php b/vendor/sabre/vobject/lib/Writer.php
new file mode 100644
index 000000000..f8a58758d
--- /dev/null
+++ b/vendor/sabre/vobject/lib/Writer.php
@@ -0,0 +1,81 @@
+<?php
+
+namespace Sabre\VObject;
+
+use Sabre\Xml;
+
+/**
+ * iCalendar/vCard/jCal/jCard/xCal/xCard writer object.
+ *
+ * This object provides a few (static) convenience methods to quickly access
+ * the serializers.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Ivan Enderlin
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Writer {
+
+    /**
+     * Serializes a vCard or iCalendar object.
+     *
+     * @param Component $component
+     *
+     * @return string
+     */
+    static function write(Component $component) {
+
+        return $component->serialize();
+
+    }
+
+    /**
+     * Serializes a jCal or jCard object.
+     *
+     * @param Component $component
+     * @param int $options
+     *
+     * @return string
+     */
+    static function writeJson(Component $component, $options = 0) {
+
+        return json_encode($component, $options);
+
+    }
+
+    /**
+     * Serializes a xCal or xCard object.
+     *
+     * @param Component $component
+     *
+     * @return string
+     */
+    static function writeXml(Component $component) {
+
+        $writer = new Xml\Writer();
+        $writer->openMemory();
+        $writer->setIndent(true);
+
+        $writer->startDocument('1.0', 'utf-8');
+
+        if ($component instanceof Component\VCalendar) {
+
+            $writer->startElement('icalendar');
+            $writer->writeAttribute('xmlns', Parser\Xml::XCAL_NAMESPACE);
+
+        } else {
+
+            $writer->startElement('vcards');
+            $writer->writeAttribute('xmlns', Parser\Xml::XCARD_NAMESPACE);
+
+        }
+
+        $component->xmlSerialize($writer);
+
+        $writer->endElement();
+
+        return $writer->outputMemory();
+
+    }
+
+}
diff --git a/vendor/sabre/vobject/lib/timezonedata/exchangezones.php b/vendor/sabre/vobject/lib/timezonedata/exchangezones.php
new file mode 100644
index 000000000..38138354a
--- /dev/null
+++ b/vendor/sabre/vobject/lib/timezonedata/exchangezones.php
@@ -0,0 +1,93 @@
+<?php
+
+/**
+ * Microsoft exchange timezones
+ * Source:
+ * http://msdn.microsoft.com/en-us/library/ms988620%28v=exchg.65%29.aspx.
+ *
+ * Correct timezones deduced with help from:
+ * http://en.wikipedia.org/wiki/List_of_tz_database_time_zones
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+return [
+    'Universal Coordinated Time'                               => 'UTC',
+    'Casablanca, Monrovia'                                     => 'Africa/Casablanca',
+    'Greenwich Mean Time: Dublin, Edinburgh, Lisbon, London'   => 'Europe/Lisbon',
+    'Greenwich Mean Time; Dublin, Edinburgh, London'           => 'Europe/London',
+    'Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna'         => 'Europe/Berlin',
+    'Belgrade, Pozsony, Budapest, Ljubljana, Prague'           => 'Europe/Prague',
+    'Brussels, Copenhagen, Madrid, Paris'                      => 'Europe/Paris',
+    'Paris, Madrid, Brussels, Copenhagen'                      => 'Europe/Paris',
+    'Prague, Central Europe'                                   => 'Europe/Prague',
+    'Sarajevo, Skopje, Sofija, Vilnius, Warsaw, Zagreb'        => 'Europe/Sarajevo',
+    'West Central Africa'                                      => 'Africa/Luanda', // This was a best guess
+    'Athens, Istanbul, Minsk'                                  => 'Europe/Athens',
+    'Bucharest'                                                => 'Europe/Bucharest',
+    'Cairo'                                                    => 'Africa/Cairo',
+    'Harare, Pretoria'                                         => 'Africa/Harare',
+    'Helsinki, Riga, Tallinn'                                  => 'Europe/Helsinki',
+    'Israel, Jerusalem Standard Time'                          => 'Asia/Jerusalem',
+    'Baghdad'                                                  => 'Asia/Baghdad',
+    'Arab, Kuwait, Riyadh'                                     => 'Asia/Kuwait',
+    'Moscow, St. Petersburg, Volgograd'                        => 'Europe/Moscow',
+    'East Africa, Nairobi'                                     => 'Africa/Nairobi',
+    'Tehran'                                                   => 'Asia/Tehran',
+    'Abu Dhabi, Muscat'                                        => 'Asia/Muscat', // Best guess
+    'Baku, Tbilisi, Yerevan'                                   => 'Asia/Baku',
+    'Kabul'                                                    => 'Asia/Kabul',
+    'Ekaterinburg'                                             => 'Asia/Yekaterinburg',
+    'Islamabad, Karachi, Tashkent'                             => 'Asia/Karachi',
+    'Kolkata, Chennai, Mumbai, New Delhi, India Standard Time' => 'Asia/Calcutta',
+    'Kathmandu, Nepal'                                         => 'Asia/Kathmandu',
+    'Almaty, Novosibirsk, North Central Asia'                  => 'Asia/Almaty',
+    'Astana, Dhaka'                                            => 'Asia/Dhaka',
+    'Sri Jayawardenepura, Sri Lanka'                           => 'Asia/Colombo',
+    'Rangoon'                                                  => 'Asia/Rangoon',
+    'Bangkok, Hanoi, Jakarta'                                  => 'Asia/Bangkok',
+    'Krasnoyarsk'                                              => 'Asia/Krasnoyarsk',
+    'Beijing, Chongqing, Hong Kong SAR, Urumqi'                => 'Asia/Shanghai',
+    'Irkutsk, Ulaan Bataar'                                    => 'Asia/Irkutsk',
+    'Kuala Lumpur, Singapore'                                  => 'Asia/Singapore',
+    'Perth, Western Australia'                                 => 'Australia/Perth',
+    'Taipei'                                                   => 'Asia/Taipei',
+    'Osaka, Sapporo, Tokyo'                                    => 'Asia/Tokyo',
+    'Seoul, Korea Standard time'                               => 'Asia/Seoul',
+    'Yakutsk'                                                  => 'Asia/Yakutsk',
+    'Adelaide, Central Australia'                              => 'Australia/Adelaide',
+    'Darwin'                                                   => 'Australia/Darwin',
+    'Brisbane, East Australia'                                 => 'Australia/Brisbane',
+    'Canberra, Melbourne, Sydney, Hobart (year 2000 only)'     => 'Australia/Sydney',
+    'Guam, Port Moresby'                                       => 'Pacific/Guam',
+    'Hobart, Tasmania'                                         => 'Australia/Hobart',
+    'Vladivostok'                                              => 'Asia/Vladivostok',
+    'Magadan, Solomon Is., New Caledonia'                      => 'Asia/Magadan',
+    'Auckland, Wellington'                                     => 'Pacific/Auckland',
+    'Fiji Islands, Kamchatka, Marshall Is.'                    => 'Pacific/Fiji',
+    'Nuku\'alofa, Tonga'                                       => 'Pacific/Tongatapu',
+    'Azores'                                                   => 'Atlantic/Azores',
+    'Cape Verde Is.'                                           => 'Atlantic/Cape_Verde',
+    'Mid-Atlantic'                                             => 'America/Noronha',
+    'Brasilia'                                                 => 'America/Sao_Paulo', // Best guess
+    'Buenos Aires'                                             => 'America/Argentina/Buenos_Aires',
+    'Greenland'                                                => 'America/Godthab',
+    'Newfoundland'                                             => 'America/St_Johns',
+    'Atlantic Time (Canada)'                                   => 'America/Halifax',
+    'Caracas, La Paz'                                          => 'America/Caracas',
+    'Santiago'                                                 => 'America/Santiago',
+    'Bogota, Lima, Quito'                                      => 'America/Bogota',
+    'Eastern Time (US & Canada)'                               => 'America/New_York',
+    'Indiana (East)'                                           => 'America/Indiana/Indianapolis',
+    'Central America'                                          => 'America/Guatemala',
+    'Central Time (US & Canada)'                               => 'America/Chicago',
+    'Mexico City, Tegucigalpa'                                 => 'America/Mexico_City',
+    'Saskatchewan'                                             => 'America/Edmonton',
+    'Arizona'                                                  => 'America/Phoenix',
+    'Mountain Time (US & Canada)'                              => 'America/Denver', // Best guess
+    'Pacific Time (US & Canada); Tijuana'                      => 'America/Los_Angeles', // Best guess
+    'Alaska'                                                   => 'America/Anchorage',
+    'Hawaii'                                                   => 'Pacific/Honolulu',
+    'Midway Island, Samoa'                                     => 'Pacific/Midway',
+    'Eniwetok, Kwajalein, Dateline Time'                       => 'Pacific/Kwajalein',
+];
diff --git a/vendor/sabre/vobject/lib/timezonedata/lotuszones.php b/vendor/sabre/vobject/lib/timezonedata/lotuszones.php
new file mode 100644
index 000000000..7d0785f04
--- /dev/null
+++ b/vendor/sabre/vobject/lib/timezonedata/lotuszones.php
@@ -0,0 +1,101 @@
+<?php
+
+/**
+ * The following list are timezone names that could be generated by
+ * Lotus / Domino.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+return [
+    'Dateline'               => 'Etc/GMT-12',
+    'Samoa'                  => 'Pacific/Apia',
+    'Hawaiian'               => 'Pacific/Honolulu',
+    'Alaskan'                => 'America/Anchorage',
+    'Pacific'                => 'America/Los_Angeles',
+    'Pacific Standard Time'  => 'America/Los_Angeles',
+    'Mexico Standard Time 2' => 'America/Chihuahua',
+    'Mountain'               => 'America/Denver',
+    // 'Mountain Standard Time' => 'America/Chihuahua', // conflict with windows timezones.
+    'US Mountain'            => 'America/Phoenix',
+    'Canada Central'         => 'America/Edmonton',
+    'Central America'        => 'America/Guatemala',
+    'Central'                => 'America/Chicago',
+    // 'Central Standard Time'  => 'America/Mexico_City', // conflict with windows timezones.
+    'Mexico'                 => 'America/Mexico_City',
+    'Eastern'                => 'America/New_York',
+    'SA Pacific'             => 'America/Bogota',
+    'US Eastern'             => 'America/Indiana/Indianapolis',
+    'Venezuela'              => 'America/Caracas',
+    'Atlantic'               => 'America/Halifax',
+    'Central Brazilian'      => 'America/Manaus',
+    'Pacific SA'             => 'America/Santiago',
+    'SA Western'             => 'America/La_Paz',
+    'Newfoundland'           => 'America/St_Johns',
+    'Argentina'              => 'America/Argentina/Buenos_Aires',
+    'E. South America'       => 'America/Belem',
+    'Greenland'              => 'America/Godthab',
+    'Montevideo'             => 'America/Montevideo',
+    'SA Eastern'             => 'America/Belem',
+    // 'Mid-Atlantic'           => 'Etc/GMT-2', // conflict with windows timezones.
+    'Azores'                 => 'Atlantic/Azores',
+    'Cape Verde'             => 'Atlantic/Cape_Verde',
+    'Greenwich'              => 'Atlantic/Reykjavik', // No I'm serious.. Greenwich is not GMT.
+    'Morocco'                => 'Africa/Casablanca',
+    'Central Europe'         => 'Europe/Prague',
+    'Central European'       => 'Europe/Sarajevo',
+    'Romance'                => 'Europe/Paris',
+    'W. Central Africa'      => 'Africa/Lagos', // Best guess
+    'W. Europe'              => 'Europe/Amsterdam',
+    'E. Europe'              => 'Europe/Minsk',
+    'Egypt'                  => 'Africa/Cairo',
+    'FLE'                    => 'Europe/Helsinki',
+    'GTB'                    => 'Europe/Athens',
+    'Israel'                 => 'Asia/Jerusalem',
+    'Jordan'                 => 'Asia/Amman',
+    'Middle East'            => 'Asia/Beirut',
+    'Namibia'                => 'Africa/Windhoek',
+    'South Africa'           => 'Africa/Harare',
+    'Arab'                   => 'Asia/Kuwait',
+    'Arabic'                 => 'Asia/Baghdad',
+    'E. Africa'              => 'Africa/Nairobi',
+    'Georgian'               => 'Asia/Tbilisi',
+    'Russian'                => 'Europe/Moscow',
+    'Iran'                   => 'Asia/Tehran',
+    'Arabian'                => 'Asia/Muscat',
+    'Armenian'               => 'Asia/Yerevan',
+    'Azerbijan'              => 'Asia/Baku',
+    'Caucasus'               => 'Asia/Yerevan',
+    'Mauritius'              => 'Indian/Mauritius',
+    'Afghanistan'            => 'Asia/Kabul',
+    'Ekaterinburg'           => 'Asia/Yekaterinburg',
+    'Pakistan'               => 'Asia/Karachi',
+    'West Asia'              => 'Asia/Tashkent',
+    'India'                  => 'Asia/Calcutta',
+    'Sri Lanka'              => 'Asia/Colombo',
+    'Nepal'                  => 'Asia/Kathmandu',
+    'Central Asia'           => 'Asia/Dhaka',
+    'N. Central Asia'        => 'Asia/Almaty',
+    'Myanmar'                => 'Asia/Rangoon',
+    'North Asia'             => 'Asia/Krasnoyarsk',
+    'SE Asia'                => 'Asia/Bangkok',
+    'China'                  => 'Asia/Shanghai',
+    'North Asia East'        => 'Asia/Irkutsk',
+    'Singapore'              => 'Asia/Singapore',
+    'Taipei'                 => 'Asia/Taipei',
+    'W. Australia'           => 'Australia/Perth',
+    'Korea'                  => 'Asia/Seoul',
+    'Tokyo'                  => 'Asia/Tokyo',
+    'Yakutsk'                => 'Asia/Yakutsk',
+    'AUS Central'            => 'Australia/Darwin',
+    'Cen. Australia'         => 'Australia/Adelaide',
+    'AUS Eastern'            => 'Australia/Sydney',
+    'E. Australia'           => 'Australia/Brisbane',
+    'Tasmania'               => 'Australia/Hobart',
+    'Vladivostok'            => 'Asia/Vladivostok',
+    'West Pacific'           => 'Pacific/Guam',
+    'Central Pacific'        => 'Asia/Magadan',
+    'Fiji'                   => 'Pacific/Fiji',
+    'New Zealand'            => 'Pacific/Auckland',
+    'Tonga'                  => 'Pacific/Tongatapu',
+];
diff --git a/vendor/sabre/vobject/lib/timezonedata/php-bc.php b/vendor/sabre/vobject/lib/timezonedata/php-bc.php
new file mode 100644
index 000000000..906ccb0e4
--- /dev/null
+++ b/vendor/sabre/vobject/lib/timezonedata/php-bc.php
@@ -0,0 +1,154 @@
+<?php
+
+/**
+ * A list of additional PHP timezones that are returned by
+ * DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC)
+ * valid for new DateTimeZone().
+ *
+ * This list does not include those timezone identifiers that we have to map to
+ * a different identifier for some PHP versions (see php-workaround.php).
+ *
+ * Instead of using DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC)
+ * directly, we use this file because DateTimeZone::ALL_WITH_BC is not properly
+ * supported by all PHP version and HHVM.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+return [
+    'Africa/Asmera',
+    'Africa/Timbuktu',
+    'America/Argentina/ComodRivadavia',
+    'America/Atka',
+    'America/Buenos_Aires',
+    'America/Catamarca',
+    'America/Coral_Harbour',
+    'America/Cordoba',
+    'America/Ensenada',
+    'America/Fort_Wayne',
+    'America/Indianapolis',
+    'America/Jujuy',
+    'America/Knox_IN',
+    'America/Louisville',
+    'America/Mendoza',
+    'America/Montreal',
+    'America/Porto_Acre',
+    'America/Rosario',
+    'America/Shiprock',
+    'America/Virgin',
+    'Antarctica/South_Pole',
+    'Asia/Ashkhabad',
+    'Asia/Calcutta',
+    'Asia/Chungking',
+    'Asia/Dacca',
+    'Asia/Istanbul',
+    'Asia/Katmandu',
+    'Asia/Macao',
+    'Asia/Saigon',
+    'Asia/Tel_Aviv',
+    'Asia/Thimbu',
+    'Asia/Ujung_Pandang',
+    'Asia/Ulan_Bator',
+    'Atlantic/Faeroe',
+    'Atlantic/Jan_Mayen',
+    'Australia/ACT',
+    'Australia/Canberra',
+    'Australia/LHI',
+    'Australia/North',
+    'Australia/NSW',
+    'Australia/Queensland',
+    'Australia/South',
+    'Australia/Tasmania',
+    'Australia/Victoria',
+    'Australia/West',
+    'Australia/Yancowinna',
+    'Brazil/Acre',
+    'Brazil/DeNoronha',
+    'Brazil/East',
+    'Brazil/West',
+    'Canada/Atlantic',
+    'Canada/Central',
+    'Canada/East-Saskatchewan',
+    'Canada/Eastern',
+    'Canada/Mountain',
+    'Canada/Newfoundland',
+    'Canada/Pacific',
+    'Canada/Saskatchewan',
+    'Canada/Yukon',
+    'CET',
+    'Chile/Continental',
+    'Chile/EasterIsland',
+    'EET',
+    'EST',
+    'Etc/GMT',
+    'Etc/GMT+0',
+    'Etc/GMT+1',
+    'Etc/GMT+10',
+    'Etc/GMT+11',
+    'Etc/GMT+12',
+    'Etc/GMT+2',
+    'Etc/GMT+3',
+    'Etc/GMT+4',
+    'Etc/GMT+5',
+    'Etc/GMT+6',
+    'Etc/GMT+7',
+    'Etc/GMT+8',
+    'Etc/GMT+9',
+    'Etc/GMT-0',
+    'Etc/GMT-1',
+    'Etc/GMT-10',
+    'Etc/GMT-11',
+    'Etc/GMT-12',
+    'Etc/GMT-13',
+    'Etc/GMT-14',
+    'Etc/GMT-2',
+    'Etc/GMT-3',
+    'Etc/GMT-4',
+    'Etc/GMT-5',
+    'Etc/GMT-6',
+    'Etc/GMT-7',
+    'Etc/GMT-8',
+    'Etc/GMT-9',
+    'Etc/GMT0',
+    'Etc/Greenwich',
+    'Etc/UCT',
+    'Etc/Universal',
+    'Etc/UTC',
+    'Etc/Zulu',
+    'Europe/Belfast',
+    'Europe/Nicosia',
+    'Europe/Tiraspol',
+    'GB',
+    'GMT',
+    'GMT+0',
+    'GMT-0',
+    'HST',
+    'MET',
+    'Mexico/BajaNorte',
+    'Mexico/BajaSur',
+    'Mexico/General',
+    'MST',
+    'NZ',
+    'Pacific/Ponape',
+    'Pacific/Samoa',
+    'Pacific/Truk',
+    'Pacific/Yap',
+    'PRC',
+    'ROC',
+    'ROK',
+    'UCT',
+    'US/Alaska',
+    'US/Aleutian',
+    'US/Arizona',
+    'US/Central',
+    'US/East-Indiana',
+    'US/Eastern',
+    'US/Hawaii',
+    'US/Indiana-Starke',
+    'US/Michigan',
+    'US/Mountain',
+    'US/Pacific',
+    'US/Pacific-New',
+    'US/Samoa',
+    'WET',
+];
diff --git a/vendor/sabre/vobject/lib/timezonedata/php-workaround.php b/vendor/sabre/vobject/lib/timezonedata/php-workaround.php
new file mode 100644
index 000000000..6b9cb6ef7
--- /dev/null
+++ b/vendor/sabre/vobject/lib/timezonedata/php-workaround.php
@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * A list of PHP timezones that were supported until 5.5.9, removed in
+ * PHP 5.5.10 and re-introduced in PHP 5.5.17.
+ *
+ * DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC) returns them,
+ * but they are invalid for new DateTimeZone(). Fixed in PHP 5.5.17.
+ * https://bugs.php.net/bug.php?id=66985
+ *
+ * Some more info here:
+ * http://evertpot.com/php-5-5-10-timezone-changes/
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+return [
+    'CST6CDT'   => 'America/Chicago',
+    'Cuba'      => 'America/Havana',
+    'Egypt'     => 'Africa/Cairo',
+    'Eire'      => 'Europe/Dublin',
+    'EST5EDT'   => 'America/New_York',
+    'Factory'   => 'UTC',
+    'GB-Eire'   => 'Europe/London',
+    'GMT0'      => 'UTC',
+    'Greenwich' => 'UTC',
+    'Hongkong'  => 'Asia/Hong_Kong',
+    'Iceland'   => 'Atlantic/Reykjavik',
+    'Iran'      => 'Asia/Tehran',
+    'Israel'    => 'Asia/Jerusalem',
+    'Jamaica'   => 'America/Jamaica',
+    'Japan'     => 'Asia/Tokyo',
+    'Kwajalein' => 'Pacific/Kwajalein',
+    'Libya'     => 'Africa/Tripoli',
+    'MST7MDT'   => 'America/Denver',
+    'Navajo'    => 'America/Denver',
+    'NZ-CHAT'   => 'Pacific/Chatham',
+    'Poland'    => 'Europe/Warsaw',
+    'Portugal'  => 'Europe/Lisbon',
+    'PST8PDT'   => 'America/Los_Angeles',
+    'Singapore' => 'Asia/Singapore',
+    'Turkey'    => 'Europe/Istanbul',
+    'Universal' => 'UTC',
+    'W-SU'      => 'Europe/Moscow',
+    'Zulu'      => 'UTC',
+];
diff --git a/vendor/sabre/vobject/lib/timezonedata/windowszones.php b/vendor/sabre/vobject/lib/timezonedata/windowszones.php
new file mode 100644
index 000000000..ac69847cc
--- /dev/null
+++ b/vendor/sabre/vobject/lib/timezonedata/windowszones.php
@@ -0,0 +1,119 @@
+<?php
+
+/**
+ * Automatically generated timezone file
+ *
+ * Last update: 2015-07-27T16:56:36-04:00
+ * Source: http://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+
+return [
+  'AUS Central Standard Time'       => 'Australia/Darwin',
+  'AUS Eastern Standard Time'       => 'Australia/Sydney',
+  'Afghanistan Standard Time'       => 'Asia/Kabul',
+  'Alaskan Standard Time'           => 'America/Anchorage',
+  'Arab Standard Time'              => 'Asia/Riyadh',
+  'Arabian Standard Time'           => 'Asia/Dubai',
+  'Arabic Standard Time'            => 'Asia/Baghdad',
+  'Argentina Standard Time'         => 'America/Buenos_Aires',
+  'Atlantic Standard Time'          => 'America/Halifax',
+  'Azerbaijan Standard Time'        => 'Asia/Baku',
+  'Azores Standard Time'            => 'Atlantic/Azores',
+  'Bahia Standard Time'             => 'America/Bahia',
+  'Bangladesh Standard Time'        => 'Asia/Dhaka',
+  'Belarus Standard Time'           => 'Europe/Minsk',
+  'Canada Central Standard Time'    => 'America/Regina',
+  'Cape Verde Standard Time'        => 'Atlantic/Cape_Verde',
+  'Caucasus Standard Time'          => 'Asia/Yerevan',
+  'Cen. Australia Standard Time'    => 'Australia/Adelaide',
+  'Central America Standard Time'   => 'America/Guatemala',
+  'Central Asia Standard Time'      => 'Asia/Almaty',
+  'Central Brazilian Standard Time' => 'America/Cuiaba',
+  'Central Europe Standard Time'    => 'Europe/Budapest',
+  'Central European Standard Time'  => 'Europe/Warsaw',
+  'Central Pacific Standard Time'   => 'Pacific/Guadalcanal',
+  'Central Standard Time'           => 'America/Chicago',
+  'Central Standard Time (Mexico)'  => 'America/Mexico_City',
+  'China Standard Time'             => 'Asia/Shanghai',
+  'Dateline Standard Time'          => 'Etc/GMT+12',
+  'E. Africa Standard Time'         => 'Africa/Nairobi',
+  'E. Australia Standard Time'      => 'Australia/Brisbane',
+  'E. South America Standard Time'  => 'America/Sao_Paulo',
+  'Eastern Standard Time'           => 'America/New_York',
+  'Eastern Standard Time (Mexico)'  => 'America/Cancun',
+  'Egypt Standard Time'             => 'Africa/Cairo',
+  'Ekaterinburg Standard Time'      => 'Asia/Yekaterinburg',
+  'FLE Standard Time'               => 'Europe/Kiev',
+  'Fiji Standard Time'              => 'Pacific/Fiji',
+  'GMT Standard Time'               => 'Europe/London',
+  'GTB Standard Time'               => 'Europe/Bucharest',
+  'Georgian Standard Time'          => 'Asia/Tbilisi',
+  'Greenland Standard Time'         => 'America/Godthab',
+  'Greenwich Standard Time'         => 'Atlantic/Reykjavik',
+  'Hawaiian Standard Time'          => 'Pacific/Honolulu',
+  'India Standard Time'             => 'Asia/Calcutta',
+  'Iran Standard Time'              => 'Asia/Tehran',
+  'Israel Standard Time'            => 'Asia/Jerusalem',
+  'Jordan Standard Time'            => 'Asia/Amman',
+  'Kaliningrad Standard Time'       => 'Europe/Kaliningrad',
+  'Korea Standard Time'             => 'Asia/Seoul',
+  'Libya Standard Time'             => 'Africa/Tripoli',
+  'Line Islands Standard Time'      => 'Pacific/Kiritimati',
+  'Magadan Standard Time'           => 'Asia/Magadan',
+  'Mauritius Standard Time'         => 'Indian/Mauritius',
+  'Middle East Standard Time'       => 'Asia/Beirut',
+  'Montevideo Standard Time'        => 'America/Montevideo',
+  'Morocco Standard Time'           => 'Africa/Casablanca',
+  'Mountain Standard Time'          => 'America/Denver',
+  'Mountain Standard Time (Mexico)' => 'America/Chihuahua',
+  'Myanmar Standard Time'           => 'Asia/Rangoon',
+  'N. Central Asia Standard Time'   => 'Asia/Novosibirsk',
+  'Namibia Standard Time'           => 'Africa/Windhoek',
+  'Nepal Standard Time'             => 'Asia/Katmandu',
+  'New Zealand Standard Time'       => 'Pacific/Auckland',
+  'Newfoundland Standard Time'      => 'America/St_Johns',
+  'North Asia East Standard Time'   => 'Asia/Irkutsk',
+  'North Asia Standard Time'        => 'Asia/Krasnoyarsk',
+  'Pacific SA Standard Time'        => 'America/Santiago',
+  'Pacific Standard Time'           => 'America/Los_Angeles',
+  'Pacific Standard Time (Mexico)'  => 'America/Santa_Isabel',
+  'Pakistan Standard Time'          => 'Asia/Karachi',
+  'Paraguay Standard Time'          => 'America/Asuncion',
+  'Romance Standard Time'           => 'Europe/Paris',
+  'Russia Time Zone 10'             => 'Asia/Srednekolymsk',
+  'Russia Time Zone 11'             => 'Asia/Kamchatka',
+  'Russia Time Zone 3'              => 'Europe/Samara',
+  'Russian Standard Time'           => 'Europe/Moscow',
+  'SA Eastern Standard Time'        => 'America/Cayenne',
+  'SA Pacific Standard Time'        => 'America/Bogota',
+  'SA Western Standard Time'        => 'America/La_Paz',
+  'SE Asia Standard Time'           => 'Asia/Bangkok',
+  'Samoa Standard Time'             => 'Pacific/Apia',
+  'Singapore Standard Time'         => 'Asia/Singapore',
+  'South Africa Standard Time'      => 'Africa/Johannesburg',
+  'Sri Lanka Standard Time'         => 'Asia/Colombo',
+  'Syria Standard Time'             => 'Asia/Damascus',
+  'Taipei Standard Time'            => 'Asia/Taipei',
+  'Tasmania Standard Time'          => 'Australia/Hobart',
+  'Tokyo Standard Time'             => 'Asia/Tokyo',
+  'Tonga Standard Time'             => 'Pacific/Tongatapu',
+  'Turkey Standard Time'            => 'Europe/Istanbul',
+  'US Eastern Standard Time'        => 'America/Indianapolis',
+  'US Mountain Standard Time'       => 'America/Phoenix',
+  'UTC'                             => 'Etc/GMT',
+  'UTC+12'                          => 'Etc/GMT-12',
+  'UTC-02'                          => 'Etc/GMT+2',
+  'UTC-11'                          => 'Etc/GMT+11',
+  'Ulaanbaatar Standard Time'       => 'Asia/Ulaanbaatar',
+  'Venezuela Standard Time'         => 'America/Caracas',
+  'Vladivostok Standard Time'       => 'Asia/Vladivostok',
+  'W. Australia Standard Time'      => 'Australia/Perth',
+  'W. Central Africa Standard Time' => 'Africa/Lagos',
+  'W. Europe Standard Time'         => 'Europe/Berlin',
+  'West Asia Standard Time'         => 'Asia/Tashkent',
+  'West Pacific Standard Time'      => 'Pacific/Port_Moresby',
+  'Yakutsk Standard Time'           => 'Asia/Yakutsk',
+];