[MMc] Body-space HUD layer working

Iron Man-style 2.5D Body Space HUD

Anyone using VRApp now has access to a virtual 2.0m-wide monitor (the DK2 is so low resolution that you need the virtual monitor to be large). It is in body space, so it is always near you, but you can move your head to see various parts of the screen at higher resolution. Everything is open source and committed to http://g3d.codeplex.com.

At this point, I've completed my goals for the jam. This is the first time I've won a jam well before the deadline. I'm very happy both with the state of the G3D development tools and my specification process this time.

I'm now working on additional polish:

1. Eliminating the one frame of latency in the tracking data, so that tracking can be sampled right before simulation
2. A better solution for dealing with body-space pitch. Currently there are inconsistent values in the camera and tracker, and the renderer just hides this
3. Deal with the cursor moving off screen (update: done! I just enforce input locking when the HUD is enabled)