fix for long standing annoyance with weight-paint mode selection.

There was no selection flushing when faces or verts were selected, this allowed incorrect selection states like selected face with unselected vertices.

add flush commands to paintface_flush_flags() and paintvert_flush_flags()


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53482 954f8c5b-7b00-dc11-b283-0030488c597c