Blender Git Loki

Rename some classes at the suggestion of reviewers.

Mesh -> IMesh; MArena -> IMeshArena
Remove type abbreviations Vertp and Facep.

GPencil: Report operators that are not implemented

LineArt: "Intersection Only" flag for objects/collections

GPencil: Remove unessesary curve edit mode test

GPencil: Draw transform gizmo curve edit

GPencil: Fix transform memory issue

Use an enum type for solver in boolean modifier.

This matches what was done in a previous commit for the tool.
It makes it easier to associate a tooltip with each choice.
For this branch, I have the default solver be the Exact one;
when we merge to master, we will have to decide the best default.
Make format caught a coouple other files, sorr for not doing those
earlier.

Add newly creates faces to imported faces and dissolve edges.

The code so far imports triangles, but also fills holes.
Committing since it doesn't crash.

test file:

```
o plane_with_hole
v 2 2 0
v 2 -2 0
v -2 -2 0
v -2 2 0

v 1 1 0
v 1 -1 0
v -1 -1 0
v -1 1 0

f 4 1 2 3 4 8 5 6 7 8 4
```

Fix tessellate crash due to wrong Vector size.

Also fix crash due to out of bound vertex indices.

Commit as it is ngon-tessellate.

The code is totally untested and will very likely crash.

GPencil: Fix handle lines display

Tests: detect memory leaks in automated tests

A memory leak should be considered a bug. Therefore, it makes sense to fail tests when they contain memory leaks.

Differential Revision: https://developer.blender.org/D8665

Use draw manager cursor

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

GPencil: Recalc transform only in curve edit mode

When changing the opacity or thickness, only reaclculate stroke if in
curve edit mode.

GPencil: Make parameters const

Merge branch 'soc-2020-greasepencil-curve' of git.blender.org:blender into soc-2020-greasepencil-curve

Merge branch 'master' into lanpr-under-gp

Merge branch 'master' into greasepencil-object

Merge branch 'master' into greasepencil-edit-curve