Implement simple Event System

[bitbrain]

Instead of defining indivual listeners per game component, have a so called EventManager:

EventManager eventManager = context.getEventManager();

It is the possible to implement custom events:

class MyTestEvent implements GameEvent { }

In order to produce:

eventManager.publish(new MyTestEvent());

In order to consume:

eventManager.register(new GameEventListener<MyTestEvent>() {
   @Override
   public void onEvent(MyTestEvent event) {
      // do something with the event
   }
});