Matt ayman frames

Redo of the merge of Frame, RigidFrame, FixedFrame, Station and Marker ModelComponents along with code to convert Marker to new format for serialization/deserialization and inclusion of FrameSet in model.
@sherm1 @msdemers @aseth1 or @chrisdembia Please review and let us know your feedback.
Would you be using an abstract RigidFrame in those cases? If you use a FixedFrame or a Body they know what Body. But if I want IntermediateScapuloThoracicFrame derived from RigidFrame you are forcing me to create and expose a Body when one is unnecessary. (Body being OpenSim::Body)