Fix car physics again

Car physics are shit.  Apparently making a decent car in ODE requires actually using wheels, and I don't have time for that.  Maybe after I get the important stuff done I'll do that, but even then, that might break the hard coded reflex agents if we're still doing those.

The main problem is that the control is kind of slippery but honestly, it behaves just like a car that's designed to drift.

Also, I added buildings.  They work fine because they don't move.  Next step - making some gamestates to pass to agents.