New event system that has more of an AS3 look-and-feel

Some quick information about this :
* A basic Observer Pattern implementation;
* Support for context-passing and event priority;
* All the same events that were there before are available through the new event system;
* Features new events such as : keyboard events, a mousewheel event, added/removed from stage events, enter/exit frame events and a catch-all event;
* There is no true capture nor bubbling phase (it works the same way it did with the previous event system);
* Users can make their own custom events, just like in flash.