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.
> A FixedFrame is a Frame (not a RigidFrame) that has a fixed (constant) transform relative to another Frame.

That doesn't work because then you can't attach a joint to a FixedFrame. There might be a use for this concept (I called it an `OffsetFrame` earlier) but it doesn't replace what we currently call `FixedFrame` (which I called `OffsetAnchoredFrame`).