improve BMesh api use from r54265, no need to do edge lookups from the faces verts since the face stores these already.

also remove ScrArea.cursor, historic runtime variable.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54266 954f8c5b-7b00-dc11-b283-0030488c597c