- sending alarms to CalDAV/GroupDAV clients as offset, not fixed time like before
- only exception to the above are alarms for recuring events to Lightning, which must be absolute, as offset lead to infinit poping up alarms in Lightning
- update all alarm times of other users alarms too, when storing events, as they might not be included in the stored event
- Lightning pops up alarm, until Sequence/etag get updated: if user has no edit rights on an other users calendar, etag never got updated, now we update it
- fixed user was not able to add alarms via CalDAV, if he had no edit rights for event (was always possible in web UI)
- alarms from other users calendars are not included any more, as they make no sense but a lot of trouble
- fixed wrong condition on adding alarms, causing some alarms no being saved
