Blender Git Commits

Port first half of the widgets to new pipeline (drawing only)

Also lots of structuring and cleanup.

Tested each button individually, seems everything is fine (menu items are doing weird things though, didn't investigate yet).

Initial refactor of interface widget architecture

Initial refactor of interface widget architecture towards the following goals:
* Widget Draw Styles (see T45025 - heavily overlaps with this)
* Isolating widget code to make it more future proof
* Adding callback based widgets handling module (currently handled in interface_handler.c)

Adds the following folders/files:
interface/widgets/
interface/widgets/widgets.c
interface/widgets/widgets.h
interface/widgets/widgets_draw/
interface/widgets/widgets_draw/drawstyle_classic.c
interface/widgets/widgets_draw/widgets_draw.c
interface/widgets/widgets_draw/widgets_draw_intern.h

Not sure if editors/interface/ is the right place for this, but depends on some further decisions.