Blender Git Loki

Rake brushes for texture paint
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* port brushes correctly to projection painting
* put rake state to unified settings, it's probably the most accessible
place for texpaint/sculpt/display functions. Ideally I would put these
in the paint or brush structs but since these are actually screen-space
state they can be unique for each space and common to all brushes. This
is in preparation to unifying brush draw code.