Default intersphinx version to python 3

doc/conf.py

@@ -193,7 +193,7 @@ latex_elements = {
     'fontpkg': r"\usepackage{bookman}"}
 
 # Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {'python': ('http://docs.python.org', None),
+intersphinx_mapping = {'python': ('http://docs.python.org/3', None),
                        'numpy': ('http://docs.scipy.org/doc/numpy', None),
                        'scipy': ('http://docs.scipy.org/doc/scipy/reference', None),
                        'matplotlib': ('http://matplotlib.sourceforge.net', None),