Matt ayman frames

Merge in branch from Hackathon to create new ModelComponents: Frame, BodyFrame, FixedFrame and Station. The functionality is tested in a separate test case testFrames and in testComponents but is not incorporated into any Models or computations yet. Please take a look at the headers and give us feedback if you plan to use this functionality. The plan is to use Frames to attach geometry, joints, wrapping etc. and to make Markers utilize Stations.
> On another note, this only saves us using ~ operator on SimTK::Transform, is there a corresponding functional equivalent to this operator?

yes, it is `invert()`