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.
>An OpenSim rigid body component. 

Is no longer correct. That is now the role of RigidFrame. Perhaps:

A Body is a RigidFrame that includes mass and inertia. The properties of the Body specify its mass, center-of-mass located in the Body frame and the moment of inertia tensor about the center-of-mass.