Blender Git Loki

Tests: add --no-window-focus to open window without focus.

This is useful to run OpenGL tests while continuing to do other tasks
without windows constantly popping up in the foreground.

Fix T56927: Grease pencil materials issues with lock and hide

GP: Fix infinite loop in Dope Sheet

Cycles: Improved ray differentials for volume scattering.

Fix missing free

UI: Tabs on right w/ right aligned regions

UI: Use "View" category for 3D view panels

Allows add-ons to add other categories.

Python GPU module: Wrap GPUIndexBuf

Differential Revision D3714

Python GPU module: replace `PyArg_ParseTupleAndKeywords` by `_PyArg_ParseTupleAndKeywordsFast`

part of T47811 ("for faster argument parsing").

Cleanup: remove star import

Tool System: expose rotate-source for click-extrude

Merge branch 'master' into blender2.8

Spin Tool: hide options unrelated to duplication

Keymap: use shift to de-deselect for tools

This allows for Ctrl-LMB
to be used for lasso even with Border-Select active.

Tool System: set a default tool for each mode

Also clear tools for the default startup file
so changes to defaults apply to new files.

Cleanup: pep8

Cleanup: flip option unlock -> lock

Nearly all options are currently to toggle locking.

Wireframe/Xray: Make Xray option local to wireframe mode

This commit make the Xray option for the wireframe different from the other
shading mode. This makes it possible to rapidly switch between wireframe +
Xray and Solid mode without Xray.

Xray alpha is also decoupled.

Both variables are duplicated and exposed separately through RNA.

UI: switch shortcuts for pivot and orientation pie menus.

Pivot is now period key, orientation is comma key.

UI: keep some buttons fixed size in 3D view header.