Blender Git Loki

Cleanup: rename uuid's related operator properties to match names used everywhere else.

Fix several issues found while working on drag and drop linking.

Append/link exec code was not handling correctly asset cases in 'single
item' case.

Also, first drag'n'drop code was slitghly too much simple, losing uuid's
on the way, had to make things a bit more convoluted...

Fix crash when opening a .blend file with an opened FileBrowser editor.

Merge branch 'id_override_static' into asset-engine

Merge branch 'master' into id_override_static

Add initial, very basic/proof-of-concept drag and drop linking.

Essentially works, will still need (as usual :P) lots of extension and
fixes and enhancements...

Merge branch 'id_override_static' into asset-engine

Merge branch 'master' into asset-engine

Conflicts:
source/blender/editors/space_file/file_ops.c

Merge branch 'master' into id_override_static

Merge branch 'id_override_static' into asset-engine

Merge branch 'master' into id_override_static

Merge branch 'id_override_static' into asset-engine

Add needed option to handle or not override's reference pointer when remapping.

There are cases where we'll want to also override the reference pointer
(when we actually switch that datablock itself), but in some specific
situations, like when creating a new override, we need to keep org
pointer here!

Merge branch 'master' into id_override_static

Merge branch 'master' into id_override_static

Merge branch 'id_override_static' into asset-engine

Conflicts:
source/blender/editors/sculpt_paint/paint_vertex.c

Merge branch 'master' into id_override_static

Merge branch 'master' into id_override_static

Add basic override generation for virtually linked assets.

Roughly working, most certainly oceans of worms are squirming
under the surface though...

Revert hack making linked virtual datablock editables.

Essentially, this reverts most ID_IS_LINKED_DATABLOCK() checks to
ID_IS_LINKED() one.

Idea of making virtual linked IDs editable was nice as a temp hack to do
quick experiment, but was never intended as final solution, correct way
to do that is to use static override, will be implemented soon.

Note that virtual library/virtually linked ID concept remains, it's
mandatory to handle mere files as assets (and potentially other, more
advanced cases in the future).