Make EventHandler generic

[fmbenhassine]

As of v1.0.1, the EventHandler interface is not generic. This requires a cast when using custom events:

public class MyEvent extends Event {
    
}

public class MyEventHandler implements EventHandler {
	
	@Override
	public void handleEvent(Event event) throws Exception {
		if (event instanceof MyEvent) {
			MyEvent myEvent = (MyEvent) event;
			// do something with myEvent
		}
	}
}

The EventHandler interface should be something like:

public interface EventHandler<E extends Event> {
    void handleEvent(E event) throws Exception;
}

to eliminate the need to do the cast.

[fmbenhassine]

Implemented in 6b72eff