Will move an event’s end date by a specific period of time.
event.moveEnd( delta )
delta is a Duration or something that will parse into a Duration.
start date will remain the same, making this method anologous to resizing an event from its end date. If you want to move both the
start and the
end together, use moveDates.
If there are other events that share the same
groupId, those events’ dates will be similarly modified.