[docs] [issue18758] Fix internal references in the documentation

Serhiy Storchaka added the comment: Here is a patch to Sphinx which helped me to search dead internal references. Not all references were fixed by proposed patches. ---------- Added file: http://bugs.python.org/file32061/sphinx_warn_refs.patch _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue18758> _______________________________________