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.
> If you all agree that a Station is any point, whether fixed to the multibody system or not ...

I don't. The multibody term-of-art "station" is used specifically to provide something narrower than "point". It means a point that is stationary with respect to a rigid body. It should not be used as synonymous with "point" or "marker". PointOfInterest might be a suitable more general term for a point that could be defined w.r.t. any Frame, but even there we might want to distinguish something fixed to the Frame from moving in the Frame. But *please* don't use "station" for that!