Called after an event has been modified in some way.
function( changeInfo )
changeInfo argument has the following properties:
|event||an Event Object with the updated changed data|
|relatedEvents||an array of other related Event Objects that were also affected. an event might have other recurring event instances or might be linked to other events with the same
|oldEvent||an Event Object with data prior to the change|
|revert||a function that can be called to reverse this action|