Tracks
* Finish pit lanes.
* Draw lines on the track.
* Handle starting grid.
* Handle pit placement.
* Add starting lights.
* Decide how to show timing information.
* Let the bumps affect the normal x and y.

Cars
* Make tires springy
* Account for wheels' angular momentum (motorcycle?).
* Allow computer-controled cars.

Bugs
* Crash sound doesn't usually play.
* Grass texture gets pinched on the inside of corners.
  Most textures should follow the the track, maybe grass shouldn't.
  Could add a tag to the material section.
* Timer is inaccurate, fast or slow depending on window size.
* (a little) Memory is leaked when reloading cars and tracks.
* Bad hinge positions should be handled gracefully.
* Car goes through suspension when bottomed out.