#46: Migrating child events to the ChildList itself.  Now in the ChildEvent that is fired whenever an element list's content changes are 2 lists: The contents of the list before the change and the contents after the change.  This way listeners can inspect the event's content data instead of relying on the list itself, whose contents may change from other threads while events are firing.
#46: Refactored some code in MuisTemplate and implemented listeners for one of 2 of its backing lists.