Add intersphinx for linking to python docs

docs/conf.py

@@ -25,7 +25,7 @@ import sys, os, string
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
-extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode']
+extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode', 'sphinx.ext.intersphinx']
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -287,3 +287,5 @@ epub_copyright = u'2013, Author'
 
 # Allow duplicate toc entries.
 #epub_tocdup = True
+
+intersphinx_mapping = {'http://docs.python.org/': None}