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.
We have to move away from defining a Set for every new component we define in OpenSim. Since a Model is an aggregate of all the other components, a ComponentIterator<T> would be more powerful for accessing all the Frames (or any other component) in the model. This wouldn't preclude model from having a property list of user-defined Frames. Connectors are agnostic to whoever owns the dependency. We should invest some effort on iterators.