Unification of brush code

Move anchored and rake options away from Sculpt struct and to
UnifiedPaintSettings where they may be used by other tools in the future
(carefree whistle...)

No functionality should change but if it does I'll follow the screams...

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53835 954f8c5b-7b00-dc11-b283-0030488c597c