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.
As per discussion and changes this is no longer accurate. A RigidFrame IS the base class for a Body and any other FixedFrame attached to a Body. One could say RigidFrame is analogous to a rigid massless body (in fact we could have a MasslessBody derive from RigidFrame or we could invent a Node where Forces can be applied and Joints can be connected) but I don't think it is necessary to say anymore. It is the base class for two concrete things that are meaningful to users and it leaves the door open for us to add more meaningful classes.