Blender Git Loki

Fix linking after recent build system changes in master

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

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

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

Merge branch 'master' into temp-openxr-buildstuff

Fix view stuck at center on session start without positional tracking

Use correct add-on branch for 'make update'

Hack: Let gizmos draw during playback to force VR gizmo redraws that way

We have to somehow force VR gizmos (i.e. the virtual camera) to
continuously redraw. Until there's a proper way to do that (e.g.
continuously redrawing certain gizmos without redrawing the rest of the
3D View), just allow playing animation to force these redraws.

Expose VR view rotation in the RNA/BPY

Merge branch 'soc-2019-openxr' into vr_scene_inspection

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

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

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

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

Merge branch 'master' into temp-openxr-buildstuff

Fix memory leak when closing Blender while VR session runs

Fix crash on undo or file load with running VR session

Allow querying VR session viewer location from Python

Not 100% sure if the output coordinates are correct, only did quick
testing of that. I'm just slowly working towards the virtual camera
feature for a regular viewport.

Also fix compile in Windows error with previous commit.

Fix two memory leaks in OpenGL Linux (X11) graphics binding

Add Py API for querying VR session state

This should be a rather important step to get the Python defined VR UIs
to work.

Also:
* Adds a bpy.types.XrSessionState.is_running() class method for
the UI to use.
* Adds a XR-data-changed notifier type for the window manager category
to ensure proper redraws on state changes.