Sizzletec/Project-Cave — pull request #6 by quinnydinny (2012-12-06 04:55:28+00:00)
Title: Collision corrections and more. 

* Collisions corrections for some tiles were incorrectly ordering vertices was causing an issue.
* Converted the the physics class into a singleton so that the physics context can be retrieved from anywhere in the program.
* Extended the TmxTiledmap class so that you may call load collisions on a tile map and toggle the collision layers visibility.
* Various code cleaning.