Order doctest dict.

Ensure compatibility between py3.5 and py3.6

docs/tutorials/further_topics/spatial_tournaments.rst

@@ -51,14 +51,14 @@ and obtain the interactions::
 
     >>> spatial_tournament = axl.SpatialTournament(players ,turns=2, repetitions=2, edges=edges)
     >>> results = spatial_tournament.play(keep_interactions=True)
-    >>> for index_pair, interaction in results.interactions.items():
+    >>> for index_pair, interaction in sorted(results.interactions.items()):
     ...     player1 = spatial_tournament.players[index_pair[0]]
     ...     player2 = spatial_tournament.players[index_pair[1]]
     ...     print('%s vs %s: %s' % (player1, player2, interaction))
-    Defector vs Tit For Tat: [[('D', 'C'), ('D', 'D')], [('D', 'C'), ('D', 'D')]]
+    Cooperator vs Tit For Tat: [[('C', 'C'), ('C', 'C')], [('C', 'C'), ('C', 'C')]]
     Cooperator vs Grudger: [[('C', 'C'), ('C', 'C')], [('C', 'C'), ('C', 'C')]]
+    Defector vs Tit For Tat: [[('D', 'C'), ('D', 'D')], [('D', 'C'), ('D', 'D')]]
     Defector vs Grudger: [[('D', 'C'), ('D', 'D')], [('D', 'C'), ('D', 'D')]]
-    Cooperator vs Tit For Tat: [[('C', 'C'), ('C', 'C')], [('C', 'C'), ('C', 'C')]]
 
 As anticipated  :code:`Cooperator` does not interact with :code:`Defector` neither
 :code:`TitForTat` with :code:`Grudger`.