Blender Git Loki

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.

UI: allow fractical unit size for layouts.

UI: use pie menu for snap, pivot and proportional editing.

* Proportional pie menu at shift+O.
* Snap pie menu at shift+S.
* Pivot pie menu at comma. Previous comma, ctrl+comma, period
and ctrl+period shortcuts for specific pivot types were removed.

Ref T56881.

Depsgraph: Add missing relation for spline IK

Solver should clearly depend on initializaiton.

Cloth: Collision improvements

This commit includes several performance, stability, and reliability
improvements to cloth collisions.

Most notably:
* The implementation of a new self-collisions system.
* Multithreading of collision detection.
* Implementation of single sided collisions and normal overrides.
* Replacement of the `plNearestPoints` function from Bullet with a
dedicated solution.

Further, this also includes several bug fixes, and algorithmic
improvements.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D3712

Addons: reactivate 'STL format' addon

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3735

Cleanup: Edit Surface & Curve engines unused code

Edit Surface: Use edit curve engine to display edit surface

It's so similar in practice that we don't need a separate engine for edit
surface overlays.

Edit Curve: Fix "show handles" option hiding nurbs segments