Retrieves events that FullCalendar has in memory.
.fullCalendar( 'clientEvents' [, idOrFilter ] ) -> Array
This method will return an array of Event Objects that FullCalendar has stored in client-side memory.
idOrFilter is omitted, all events will be returned.
idOrFilter is an ID, all events with the same ID will be returned.
idOrFilter may also be a filter function that accepts one Event Object
argument and returns
true if it should be included in the result set.