Files size was drawn wrong when more pages were loaded
Trying to fix crashes with timers (probablility is now lower in testing, but might still happen) - don't access context at all.

Fixes QCD slots being unable to be toggled on when they contain
objects in edit mode.
Fixes an error when toggling and there is no active object.

Otherwise this can break generation of deliberately asymmetric rigs.

until now, cancelling a download always cancelled the last download, not the one clicked on

This function seemed to be doing a lot of unneccessary stuff, including mode switching, so it seemed worthwhile to optimize a bit.

No functional changes.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D8514

This class exists specifically for the purpose of defining and drawing the UI for bone layer assignment parameters, as seen in other rig types like super_chain, limb_rigs, simple_tentacle, etc. Only super_face was missing it for some reason.

Although the way it is used may be questionable, it's consistent with the rest of the codebase.

No functional changes.

Note for future: I would also like to use the ControlLayersOption class in even more places, and also maybe rename it and make improvements to it as needed. This would also be part of a bigger design of how Rigify handles bone organization, which I should write down.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D8802

Permit missing texture.source

Instead of implementing the 2 rows of layer boolean toggles, we can just use the 'LAYER' subtype on the BoolVectorProperty.

No functional changes.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D8801