Add next() for Python 2 compatibility.

IPython/core/display.py

@@ -788,6 +788,10 class ProgressBar(DisplayObject):
         else:
             raise StopIteration()
 
+    def next(self):
+        """Python 2 compatibility"""
+        returun self.__next__()
+
 class JSON(DisplayObject):
     """JSON expects a JSON-able dict or list