Removed Layer class

And changed Environment into its own class, and turned the collection of
entities into a list. Was kinda a bs idea
Added 2DList class

Also removed callback from mainLoop. (Damn that was stupid.)
Expanded 2DList and moved it to the top

+ some other minor things
Lots of changes

- changed 2DList to List2D because classnames starting with numbers are
bad apparently
- Made 2DList index-accesible
- Fixed all class methods (I'm stoopid)
- Fixed some indentation
- Fixed some __init__()s
- Some work on Player and Environment
- Some work on handleInput() and handleDraw()
- Changed mainLoop() callback to while loop (yeah that was stupid)
- other small things