cleanup of the universe setup utility, and some speed improvementt to the collision detection.
Breaking down the various physics classes, so that they will be easier to mix and match in the future. Also, better comments on the setup functionality.
Improving speed of isOverlapping method.
mend
Ignoring Shell theorem, as collisions should render it unecessary. Uncommenting out the grid setup, so that fixes can be made to the 3d rotation of camera.
Reformating directory structure.
Fixing bug with camera rotation.