split independent classes out of Ragdoll files
implement base Ragdoll::stepRagdollForward()
implement VerletPoint::integrateForward()
create MuscleConstraint for driving ragdolls
MuscleConstraints for ragdoll; velocity for verlet points
merge upstream/master into andrew/ragdoll
fix bad variable name
Merge pull request #3214 from AndrewMeadows/ragdoll

Ragdoll Part 6: muscle constraints for driving Ragdoll and also damped velocity integration for verlet simulation