More levels and world select screens

[lschmid83]

Due to time constraints I only created a limited number of levels for this game. The code is in place to implement different game worlds containing up to 8 levels. It is more of a time constraint issue where someone would have to take the time to build the levels in the editor. Another proposal is that using AI or procedural level generation we could generate an infinite number of levels based on different precompiled level tile patterns.