Bugfix #4055: the "sel" attributes for faces/edges/verts were basically

oblivious of each other, so setting/clearing the face edit mode select status
did not set/clear the corresponding vertex select statuses.  This patch makes
a change of any select status recalculate the selection state of all edges an
faces.  One unresolved issue is what effect this should have on the recent
edge mesh's stored selection.  Currently changing the selection state will
delete store selection info, but it may be desirable to emulate the stored
selection (but I need to discuss how this should work in more depth with
Geoffrey Bantle).

As an added bonus (while I was messing with this), I added a "sel" attribute
to edges so they are the same as faces and vert.

source/blender/python/api2_2x/doc/Mesh.py

@@ -89,8 +89,9 @@ done once.
     - ALPHA - draw with transparency.
     - SUB - subtract from background.
 @var EdgeFlags: The available edge flags.
-    - SELECT - selected.
+    - SELECT - selected (B{deprecated}).  Use edge.sel attribute instead.
     - EDGEDRAW - edge is drawn out of edition mode.
+#    - EDGERENDER - edge is drawn out of edition mode.
     - SEAM - edge is a seam for UV unwrapping
     - FGON - edge is part of a F-Gon.
 @type AssignModes: readonly dictionary.
@@ -327,6 +328,8 @@ class MEdge:
   @type flag: int
   @ivar index: The edge's index within the mesh.  Read-only.
   @type index: int
+  @ivar sel: The edge's B{edit mode} selection state (selected=1).
+  @type sel: int
   """
 
   def __iter__():