Validation for event reference

As I already mentioned in this previous post I wanted to add to the event validator a way to validate whether a event reference is valid or not.

What's a event reference?
It's a way to call an event from within another event. (programming metaphore: if an event is a function an event reference is a call to that function)
Anyway, I'll explain that better in a event tutorial.



Anyway, having that check is really useful. In fact there where already 4 bad reference in some older events, that now are fixed.