[API Review] FXML: Property handlers should take 3 parameters instead of Event

[Martin Sladecek]

Hi,

I propose to support Property handlers that are similar to 
ChangeListener (used to listen on property changes) and accept 
(ObservableValue, T, T), where T can be of any class. Failure to provide 
a class that is a the same or supertype/interface of the real class will 
result in CCE (as it's currently in Event handlers).

The previous Event handlers will be still supported, as this is a 
feature from 2.2.

Thanks,
-Martin