Update sphinx to 1.7.9

[pyup-bot]

This PR updates Sphinx from 1.7.7 to 1.7.9.

Changelog

1.7.9

=====================================

Features added
--------------

* 5359: Make generated texinfo files reproducible by sorting the anchors

Bugs fixed
----------

* 5361: crashed on incremental build if document uses include directive

1.7.8

=====================================

Incompatible changes
--------------------

* The type of ``env.included`` has been changed to dict of set

Bugs fixed
----------

* 5320: intersphinx: crashed if invalid url given
* 5326: manpage: crashed when invalid docname is specified as ``man_pages``
* 5322: autodoc: ``Any`` typehint causes formatting error
* 5327: "document isn't included in any toctree" warning on rebuild with
generated files
* 5335: quickstart: escape sequence has been displayed with MacPorts' python

Links

• PyPI: https://pypi.org/project/sphinx
• Changelog: https://pyup.io/changelogs/sphinx/
• Homepage: http://sphinx-doc.org/

[pyup-bot]

Closing this in favor of #35