Finished a new enemy and added a store

Finished a new enemy for the twilight themed zone (even though for this gif the enemy is in another theme, just for testing purposes). This guy will the next prototype.

Also I modified the level generator so it adds a small cave where this store can be found (please take note of the awesome placeholder art). The store will trade skulls for special items. Not sure if I can get is done before the next prototype, but I'll do the best I can.