ProSonic Tweaks

Plans to help Glu Mobile in porting Sonic the Hedgehog have stalled for the moment due to some technical issues. So for now, I'm shifting my focus back to adding features to the ProSonic engine. What I've done recently is bug fixing. I fixed a couple problems that would cause the program to crash, and I made it so the screen can't move outside the level area. In addition, I made the engine multi-level, meaning you can now move from one level to another. Before, I had the level files hard-coded into the engine, and it was configured to open whatever file I programmed it to open. I also made it so it will read a list to see what levels come in what order.