Blender Git Loki

Initial/backend support for animating settings of Grease Pencil datablocks

This commit makes it possible to insert keyframes for the line thickness,
opacity, colour, and even volumetric/non-volumetric options. It is useful
to be able to do this in order to control the thickness of lines when the
camera is placed quite close.

Notes:
* Currently, apart from the keyframe status indicator colours applied to the
buttons, these keyframes are not shown anywhere. Support for this will be
added to the animation editors shortly, but for those who need this functionality,
it's better that it works in some way first :)
* No support for drivers exists yet. This may still get supported a bit later...

GP RNA: Use soft min/max on the line thickness property to make it more controllable

Don't show GP stroke verts when doing OpenGL renders

Merge branch 'master' into GPencil_EditStrokes

Merge branch 'master' into GPencil_EditStrokes

Tweak to stroke editing drawing - Only show stroke points when in editmode

Compile fix for changes in master

Merge branch 'master' into GPencil_EditStrokes

Don't show "New Layer" operator when no GPencil datablock exists anymore

Fix for UI api changes in master

Merge branch 'master' into GPencil_EditStrokes

Conflicts:
source/blender/editors/gpencil/gpencil_buttons.c

Fix: Stroke filling was incorrectly propagated to the following layers

This was noticeable when the enabling onion skinning on a layer without
fills which follows one which does.

Merge branch 'master' into GPencil_EditStrokes

Revert "All editable GPencil stroke points are now shown when editing is enabled"

This reverts commit 9686e48bab7340a172b0c9b8aea1f685b531d29c.

In response to feedback, I've decided to revert this since it didn't really work
that great at all when you have dense drawings. At times, this would make it
almost impossible to see what you were doing.

Code cleanup: Replace all the poll callbacks with a single one

Select More/Less for Grease Pencil points

All editable GPencil stroke points are now shown when editing is enabled

The intention of this change is to make it easier to tell when you are in
stroke editing mode.

Notes:
* Even so, it isn't always obvious that these verts are being shown,
especially when the colors of the unselected points match the stoke
color OR when multiple overlapping strokes are drawn in the same place.
* It's also worth noting that pivoting away from the modal workflow again
(even though we've tried the non-modal one, and it was quite a clumsy failure)
is going to start becoming a lot harder.

RNA: Fix for missing Grease Pencil updates

Merge branch 'master' into GPencil_EditStrokes

Fix: After using Alt-SelectMouse to select an entire stroke, it would be impossible to select normally again