Blender Git Loki

Viewport HMD integration using OpenHMD

= Viewport HMD integration using OpenHMD =

This adds initial support for controlling the viewport view using a head mounted display (HMD).

To use it, go to the Properties Editor, Render Layers context. Enable Views, select "HMD View". You can then open a new HMD Window from there and start a HMD session.

**TODOs:**
* Move HMD options to a better place, they are not Render Layer related (Maybe properties region?)
* Zoom and pan don't work in HMD window while in camera view
* View streched vertically in HMD window while not in camera view
* TODOs/XXXs marked in code (esp. WM_ calls in BKE_)
* Apply D1350 for better mouse interaction while in HMD view

Reviewers: sergey, dfelinto

Differential Revision: https://developer.blender.org/D2133