Blender Git Loki

Refactor: use new api for direct linking lattice, world, camera, speaker, sound, lightprobe and collection

Refactor: use new api for direct linking light, vfong, text, ipo and key

Refactor: use new api for direct linking mball, material, texture and image

Tests: almost finished with the protoype, added support for
generating vertex groups from script.

Some minor improvements left, work in progress, saving.

Refactor: use new api for direct linking mesh and curve

Refactor: use new api for direct linking scene and object

Refactor: use new api for direct linking hair, pointcloud, volume and simulation

Refactor: use new api for direct linking screen and gpencil

Refactor: use new api in direct_link_windowmanager

Blenloader: simplify list reading api

GPencil: New prop to determine if a stroke is using Curve Edit mode

This flag will be used to determine if the selection must be done for points to generate handles or the handles are already visibles.

Merge branch 'greasepencil-edit-curve' into soc-2020-greasepencil-curve

Namespace in lower case; rename dummy UI settings

Since capitalised namespaces could cause confusion with classes, they
are changed to lower case, in uniformity with the rest of the code.

Also, in some old settings in exporter file selector are renamed to
show that they do nothing. As William Reynish suggested on devtalk
feedback thread, at some point, it'd be good to have them drawn with
python panels. [1]

[1]: devtalk.blender.org/t/13528/2

GPencil: Fix Selection mode buttons in Beziser submode

Also changed the BEZIER flag bit becaus ethe previous was already used.

GPencil: Include last GSoC commits

Minor update due merge error in writefile.c

Merge branch 'greasepencil-edit-curve' into soc-2020-greasepencil-curve

GPencil: Add edit curve mode toggle button

Merge branch 'master' into greasepencil-edit-curve

Merge branch 'master' into greasepencil-object

Fix T77473: Removing GPencil vertex group mix data

When removing a vertex group from a Grease Pencil object, if the vertex group is not the last one that was added, the information for the remaining groups weights gets mixed up.

Minor edit of the patch for clang format.

Differential Revision: https://developer.blender.org/D7943