regenerate tutorial script diffs

doc/source/images/ab_ring.py.diff

@@ -97,7 +97,7 @@
      # Finalize the system.
      sys = sys.finalized()
 @@ -111,6 +169,17 @@
-                                                 for i in xrange(100)])
+                                                 for i in range(100)])
  
  
 +    # Finally, some plots needed for the notes

doc/source/images/graphene.py.diff

 --- original
 +++ modified
-@@ -11,5 +11,6 @@
+@@ -10,6 +10,7 @@
+ #  - Application of all the aspects of tutorials 1-3 to a more complicated
  #    lattice, namely graphene
  
 +import _defs