Blender Git Loki

Merge branch 'modifier-panels-ui' of git.blender.org:blender into modifier-panels-ui

Refactor saving and setting list panel expansion

The public functions are named more sanely and their requirements are
much simpler, with more of the logic handled internally by interface_panel.c.

Also solves a bug saving and loading sub-subpanel expansion.

Alembic: keep references to the schema objects

These references are necessary for Alembic to have proper bookkeeping.
Without them, you get errors that a property `N` already exists when
exporting mesh normals.

Merge branch 'temp-checkbox-layout-tweaks' into modifier-panels-ui

Fix pointer properties breaking column layouts

Merge branch 'master' into temp-checkbox-layout-tweaks

Merge branch 'master' into greasepencil-object

Alembic: fixed time sample test

Resolve const warning for panel data reordering

Tests: On Linux, use Python from install dir

CentOS on the buildbot still runs Python 3.6, which is also used for the
unit tests. This means that the tests can't use language features that
are available to Blender itself. And testing with a different version of
Python than will be used by the actual code seems like a bad idea to me.

This commit tries to find Python in the installation directory, which
will not be there on the first time CMake is run, so it also tries to
find it in the precompiled libraries. If that also fails, it defaults to
whichever Python executable CMake finds.

Differential Revision: https://developer.blender.org/D7395

Alembic exporter: unit tests are compiling

Fixed merge error

Alembic: even nicer subsurf disable method

This is less dependent on the exact implementation of AbstractHierarchyIterator
and also avoids an evaluation of the subsurfs before they are disabled.

Alembic: nicer way to disable subdivision surfaces

Before exporting starts, subdivision surfaces are disabled. The old
Alembic exporter would do this temporarily for each frame.

Merge branch 'master' into temp-checkbox-layout-tweaks

Merge remote-tracking branch 'origin/master' into temp-alembic-exporter-T73363-ms2

Alembic: new mesh writer seems to work

Also extracted axis conversion functionality from `abc_utils.h`.

Gpencil: Cleanup unused code

Tests runner: use Python from install dir, and break if not found

Merge branch 'master' into greasepencil-object