Blender Git Loki

Merge branch 'master' into undo-experiments

USD: renamed `should_export_object` to `should_visit_object`

GPencil: Add layer operators to Dopesheet Header

USD: Revamped building & bundling process

- USD is now built as monolithic library, instead of 25 smaller
libraries. We were linking all of them as 'whole archive' anyway, so
this doesn't affect the final file size. It does, however, make life
easier with respect to linking order, and handling upstream changes.
- The JSON files required by USD are installed into bin/usd; they are
required on every platform.
- USD is patched so that it finds the aforementioned JSON files in a path
relative to the running executable. When left unpatched, the only way
to influence the search path for those files is to set an environment
variable BEFORE Blender starts (USD uses static initialisers, so by
the time the USD exporter runs, it has already unsuccessfully tried
loading the JSON files, and won't re-investigate that environment
variable ever again).
- USD is patched to have a `PXR_BUILD_USD_TOOLS` CMake option to disable
building the tools in its `bin` directory. This is sent as a pull
request at https://github.com/PixarAnimationStudios/USD/pull/1048

USD: Avoid crash when USD JSON files cannot be found

USD ships with a set of JSON files that define which formats can be written
and which plugins are required. This is used even when statically building
and only using the default USDA and USDC formats.

Fully WIP code.

Don't have proper solution yet for issue described in comment in
readfile.h, still investigating...

Overlay Engine: Fix issue with facing overlay

Render using the default view instead of the jittered view.

Cleanup: Missing bracket.

GPencil: Keep current Tool when reset all brushes

Merge branch 'master' into greasepencil-object

GPencil: Simplify Reset All brushes code

LANPR: Camera shift value assign.

Merge remote-tracking branch 'origin/master' into temp-lanpr-review

LANPR: Remove debug print in triangle clipping

LANPR: Removed camera references in RenderBuffer. Safe for thread ops.

LANPR: Locking parent thread when loading scenes into lanpr.

LANPR: Renderbuffer creation changed to re-init.

LANPR: Const qualifiers for some of the functions

Merge branch 'master' into greasepencil-object

Conflicts:
source/blender/blenloader/intern/versioning_280.c

GPencil: Check NULL Pointer