Cleanup, move uv sculpt specific code to sculpt_uv.c. Also rename
brush_drawcursor to a more indicative of its users name until paint
cursor unification is done.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54995 954f8c5b-7b00-dc11-b283-0030488c597c