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.
@aseth1 It seems like people will want to wrap the connection-setting with accessors like this. I know you and @sherm1 were briefly discussing using macros to make the connectors. Those macros could automatically generate these cleaner accessors and ensure a more uniform interface. This probably isn't something to tackle in this PR, but I just wanted to raise the point.