Sets an event’s
end date, and
allDay properties at the same time.
event.setDates( start, end, [ options ] )
end are parameters that must parse into a Date Objects.
end can be null, in which case the end date will be cleared.
options is an optional plain object that can have the following property:
false. will modify this event’s
If there are other events that share the same
groupId, those events’ dates will be similarly modified.