Update docutils to 0.17.1

[pyup-bot]

This PR updates docutils from 0.16 to 0.17.1.

Changelog

0.17.1

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

0.17.1b.dev

* Bug fixes (for details see the Docutils `HISTORY`_).

0.17

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

* Numerous bug fixes and improvements
(for details see the Docutils `HISTORY`_).

* Installing with ``setup.py`` now requires setuptools_.
Alternatively, install with pip_.

* The generic command line front end tool docutils-cli.py_ allows
the free selection of reader, parser, and writer components.

* Support Arabic language.

* New, **experimental** wrapper to integrate the `recommonmark`__
Markdown parser for use with Docutils.
Currently only tested with recommonmark version 0.4.0.

__ https://pypi.org/project/recommonmark/

* HTML5 writer:

- New option embed_images_.

- Use semantic tags (for details see the Docutils `HISTORY`_).

- Change the `initial_header_level`_ setting's default to "2", as browsers
 use the `same style for <h1> and <h2> when nested in a section`__.

- New optional style ``responsive.css``, adapts to different screen
 sizes.

- Move non-essential styling from ``minimal.css`` to ``plain.css``
 rsp. ``responsive.css``.

- Show code line numbers as pseudo-elements so they are skipped when
 copying the code block from the page.

.. _initial_header_level: docs/user/config.htmlinitial-header-level
__ https://stackoverflow.com/questions/39547412/same-font-size-for-h1-and-h2-in-article
.. _embed_images: docs/user/config.htmlembed-images

* LaTeX writer:

- New configuration setting `legacy_class_functions`_.

- The special value "auto" for the `graphicx_option`_ setting
 is no longer supported (it never worked for xetex/luatex).

- `Styling commands`__ using the legacy ``\docutilsrole`` prefix are
 now ignored. Use ``\DUrole``.

 __ docs/user/latex.htmlclasses

- Most helper commands and element definitions are now defined in the
 LaTeX package `docutils.sty`_ and only inserted in the document
 preamble if the stylesheet__ setting does not lists "docutils".

 __ docs/user/config.htmlstylesheet-latex-writers

- Remove legacy LaTeX stylesheet ``docutils-05-compat.sty``.

.. _setuptools: https://pypi.org/project/setuptools/
.. _pip: https://pypi.org/project/pip/
.. _docutils-cli.py: docs/user/tools.htmldocutils-cli-py
.. _legacy_class_functions: docs/user/config.htmllegacy-class-functions
.. _graphicx_option: docs/user/config.htmlgraphicx-option
.. _docutils.sty: https://ctan.org/pkg/docutils

Links

• PyPI: https://pypi.org/project/docutils
• Changelog: https://pyup.io/changelogs/docutils/
• Homepage: http://docutils.sourceforge.net/