Blender Git Loki

Python: Expose WM is_interface_locked to python.

This patch exposes the Window Manager `is_interface_locked` as a read
only property to python.

This property is needed to allow script writers to detect if a job is
running with locked interface like the Alembic exporter.

Reviewed By: Brecht

Differential Revision: https://developer.blender.org/D6749

Fix many typos and other issues in UI messages.

Cleanup: Alembic, split source files into reader and writer

This separation between reader and writer code is part of Milesone 2 of
T73363.

In this commit the reader and writer classes are separated into their
own files, any `#include` and `using` statements are cleaned up, and
some separator comments have been removed.

No functional changes.

Fix macOS LLVM precompiled link error with older Xcode versions

Alembic: fix unit test on Windows

There are two issues solved in this commit:

- Our Windows buildbot has slightly different floating point errors than
the Linux one, which meant a larger delta was required for float
comparisons.
- The test performs an export to a temporary Alembic file and
subsequently imports it. Deleting the temporary file was impossible on
Windows because it was still in use. This is now resolved by first
loading the default blend file before deleting the Alembic file.

UI: Use crosshair cursor for Extrude to Cursor tools

Since this tool doesn't perform selections when you click, it's important that the cursor helps communicate that something else will happen.

Also fix missing 'to' in Curve Edit Mode.

Keymap: minor tweaks so box-select shortcuts show in the menu

GPencil: Fix unreported move to layer with lock material

The strokes with the material locked could be moved. Now the lock is respected.

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

add draw function to socket

remove prints

make new socket type callbacks work

Merge branch 'master' into id-ensure-unique-memory-address

initial socket init/copy/free interface

Fix some issues with versionning of older files.

Consequences of own refactor of usercount handling in readfile.c
(rB367ecff15d74).

Not super happy to have to call that function twice, but that should be
OK (not a real overhead here anyway).

another test socket