Issue 118: assert dispatched event type is registered.
Issue 118: assert dispatched event type is registered.

niklaskorz/pyglet,niklaskorz/pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64,adamlwgriffiths/Pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64,niklaskorz/pyglet,niklaskorz/pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64