renamed Trackball to TouchTrackball. Will be refactoring Gyroscope and
TouchTrackball to inherit from a new abstract class Trackball
gracelessly split TouchTrackball into TouchTrackball and Trackball using
automatic refactoring. Needs much refinement, which will follow
added a new Joint class. I think this will serve as a new basis for
Trackball and BVHNode
added code to compute quaternions, and made backups of trackball and camera, as they will be severely changed during the rebase on Joint