Rust + OpenGL spinning cube in Looking Glass

In case anyone else out there has an interest in using Looking Glass without Unity, here’s my try at the classic Hello World of 3D, the spinning cube! It’s still a bit rough around the edges, in particular I want to clean up the OpenGL state management, and put something other than a flat colour background behind the cube so the 3D-ness is more obvious. I think this should be cross-platform to the extent that glutin and libhid is, but have only run it from Ubuntu 18.04 so far. Comments, questions, beer, Pull Requests all appreciated!