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.
@aseth1 The changes in Marker and IK in this PR are examples.

If a RigidFrame is by definition rigidly affixed to a MobilizedBody, then it always has a MobilizedBody and it always has a fixed transform in that MobilizedBody.  If we are fixing joints and forces to all classes of type RigidFrame, even one's we'll invent later, then ALL RigidFrames must be able to answer who it's mobilized body is and what the transform on the mobilized body is.  After looking at Marker, IK, Assembly conditions, etc, providing ONLY ground transforms isn't good enough.

Yes, _mbTransform holds the complete Transform from a chain of FixedTransforms.