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.
I did not participate in the design discussion, but are RigidFrame's always fixed in a Body? If so, then this should always be true.

Does this method indicate whether this RigidFrame currently has a reference to an anchor Body, or does it indicate whether this RigidFrame is supposed to be anchored to a rigid body? If the former, can we use a different name for the method, like "anchorBodyIsSet()"? "isAnchorBodySet()". Or the user could just a null reference (is that a thing?) when calling getAnchorBody().