Stuff to cleanup

[TheJosh]

This is an incomplete list. Some of these are larger tasks and should be fleshed out in their own issue.

• Wall entities need removing or rewriting; perhaps should be a start and end vector, thickness and cap type then an auto-created mesh.
• Map-related classes to be moved to own files.
• Less header dependencies for faster compiles. Cleaner interfaces.
• Remove dead or underused methods.
• Move more state from GameState into PlayerState to fix outstanding split-screen bugs.
• Clean up the mess we call the GameState class
• Split the RenderOpenGL classes up into parts, perhaps even hot-swappable at different quality levels.
• Rename "sprite" to something more appropriate.

[TheJosh]

Migrated to http://chaoticrage.com/dev_docs/what_should_i_work_on/stuff_to_cleanup