Remove index.html template and use markup in index.txt instead.

Using reStructuredText to build the front page is a bit easier to maintain.

doc/source/conf.py

@@ -148,7 +148,7 @@ html_static_path = ['_static']
 
 # Additional templates that should be rendered to pages, maps page names to
 # template names.
-html_additional_pages = {'index': 'index.html'}
+# html_additional_pages = {}
 
 # If false, no module index is generated.
 #html_use_modindex = True