Adding head tracking support for the Rift.
Moving all of the Oculus Rift things out of main and into the new RiftMode.
Adding new files for RiftModes and RiftCamera
Adding in support for when the Rift isn't attached.
Seperating out some of the shading stuff into a hierarchy of sorts.
Changing the shaders into a hierarchy, which requires changing how they're used throughout the project.
Merging the RiftDev branch into the master branch.