guidedSubdivisionIterator: add context parametr

groupConnectivity.pyx

@@ -163,7 +163,7 @@ def subdivisionIterator(G, edges = None):
       yield L
 
 
-def guidedSubdivisionIterator(G, edges = None, guide = lambda H: (True, None)):
+def guidedSubdivisionIterator(G, edges = None, guide = lambda H: (True, None), context = None):
   class DeadEnd(Exception):
     pass
 
@@ -172,7 +172,10 @@ def guidedSubdivisionIterator(G, edges = None, guide = lambda H: (True, None)):
 
   def impl(G, edges):
     if len(edges) == 0:
+      if context is None:
         cont, val = guide(G)
+      else:
+        cont, val = guide(G, context)
       if not cont:
         raise DeadEnd()
       yield val