Adds a floor

Got collisions with things to work.  Added a floor to stop cars from falling into nothing.  Tied ODE quaternion to OGRE quaternion so any rotation in the physics sim is reflected in the rendering of the game world.

TODO:
* make floor not spongy
* make cars not roll when you apply force to them
* make friction better
* convert actions from agents into forces and whatnot
* construct game states to pass into the agents
* dhsadhaskdah