cars now turn and accelerate properly fuck physics

* makes floor not spongy
* cars no longer roll when you apply forces to them
* cars can turn and accelerate
* pedestrians are doing weird things because pedestrians are weird

TODO:
* make pedestrians not broken anymore
* convert actions from AI agents into physics stuff
* construct game states to pass to agents
* construct a basic map to run this on

I'm actually almost done.  Oh my god.