add set __getitem__ method, this allows python iterator syntax to work, as in 'for i in a_set:...'

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@7338 626c5289-ae23-0410-ae9c-e8d60b6d4f22

Examples/test-suite/python/std_containers_runme.py

@@ -91,4 +91,14 @@ v3 = std_containers.vector_piA(v2)
 v3[0][1].a
 v3[1][1].a
 
+s = std_containers.set_i()
+s.append(1)
+s.append(2)
+s.append(3)
+j=1
+for i in s:
+  if i != j:
+    raise RuntimeError
+  j = j + 1
+