Blender Git Loki

Add XR_ prefix like now in master

Merge branch 'soc-2019-openxr' into vr_scene_inspection

Merge branch 'temp-openxr-blenderside' into soc-2019-openxr

Add XR_ prefix like now in master

Merge branch 'temp-openxr-ghostxr' into temp-openxr-blenderside

Add XR_ prefix like now in master

Merge branch 'temp-openxr-directx' into temp-openxr-ghostxr

Merge branch 'master' into temp-openxr-directx

Support mirroring the VR view in regular 3D Views

Adds a per 3D View option to mirror the 3D session view. When enabled,
the viewport (continuously) renders using the same location and rotation
as the 3D view. While navigation is disabled then, other interactions
are working, so you can select and edit data as usual.
To be precise, we use the pose of the centroid, not the ones used by the
eyes.

Extra attention was put into forbidding viewport navigation while the VR
mirror runs (it overrides the current viewpoint anyway). Tried to make
this a generic feature. There may still be some navigation operators
that are not covered. So using them while the mirror runs will have an
affect on what you see once you end the session or mirroring.

Quadview is preserved, only the un-locked view shows the mirror then.
All of this is runtime data, no state changes should end up being read
from saved files.

Fix build error after changes from last merge

Merge branch 'soc-2019-openxr' into vr_scene_inspection

Merge branch 'temp-openxr-blenderside' into soc-2019-openxr

Update oculus.json file for the Oculus runtime on Windows

Fix compiler warning on Linux, swapping with wrong type

Bring back vertically mirrored drawing for DirectX compatibility

Always do versioning code, even with WITH_OPENXR disabled

Always generate XR-RNA, even with WITH_OPENXR disabled

Cleanup: Move struct forward declaration to top of header

Merge branch 'temp-openxr-ghostxr' into temp-openxr-blenderside

Merge branch 'temp-openxr-directx' into temp-openxr-ghostxr