1. Fixed a bug in the OsgLine's application of force. It was not calculating the position of the world correctly. It would work fine as long as the force application was at the COM of the body, but if it was offset then it got all wonky.
2. Split out the addForce method on RigidBody and IPhysicsBody into two methods: AddForceAtLocalPos and AddForceAtWorldPos. This allows us to specify whether we are adding a force using the local body coords for the position, or world coordinates.
3. Started adding a new test for muscles/springs/force stims based on a balance beam so I can test this offset COM issue.
Got the tutorial stretch receptor and limb stiffness tests working for bullet.