[Inf-IT DAVcl] InfCloud: LAST-MODIFIED after event update

If an event has a LAST-MODIFIED:

LAST-MODIFIED;VALUE=DATE-TIME:20190308T231001Z

this seems not to be recognized by InfCloud. As a result, when changing the event via InfCloud, an additional LAST-MODIFIED is added:

LAST-MODIFIED:20190309T090207Z ... LAST-MODIFIED;VALUE=DATE-TIME:20190308T231001Z

Other caldav systems, e.g. ownCloud, then reject this event as being invalid.

I'm not quite sure who to blame...

-- Johan