1. Found a bug in spring where the prev length was not getting reset correctly in resetSimulation method. This caused the tension in the first step of the next run of the simulation to be inocrrect.
2. Added some code to ignore two small sections of data in the muscle test when it is being stretched/relaxed.
3. fixed an issue with adding forces to a body. In vortex it uses the world position of the applied force, in bullet in uses the difference from the COM in world cooredinates.
4. Found a bug in the reporting of body forces/torques. I will need to fix this in next checkin.