// TODO include timezone informations in cases were the time is not in UTC
// see http://tools.ietf.org/html/rfc2445#section-4.8.3
// . 'BEGIN:VTIMEZONE' . PHP_EOL
// . 'TZID:' . $tz . PHP_EOL
// . 'END:VTIMEZONE' . PHP_EOL;
// TODO include timezone informations in cases were the time is not in UTC
// see http://tools.ietf.org/html/rfc2445#section-4.8.3
// . 'BEGIN:VTIMEZONE' . PHP_EOL
// . 'TZID:' . $tz . PHP_EOL
// . 'END:VTIMEZONE' . PHP_EOL;