Update tox to 3.1.1

[pyup-bot]

This PR updates tox from 2.9.1 to 3.1.1.

Changelog

3.1.0

------------------

Bugfixes
^^^^^^^^

- Add ``ignore_basepython_conflict``, which determines whether conflicting
``basepython`` settings for environments containing default factors, such as
``py27`` or ``django18-py35``, should be ignored or result in warnings. This
was a common source of misconfiguration and is rarely, if ever, desirable from
a user perspective - by :user:`stephenfin` (`477 <https://github.com/tox-dev/tox/issues/477>`_)
- Fix bug with incorrectly defactorized dependencies (deps passed to pip were not de-factorized) - by :user:`bartsanchez` (`706 <https://github.com/tox-dev/tox/issues/706>`_)


Features
^^^^^^^^

- Add support for multiple PyPy versions using default factors. This allows you
to use, for example, ``pypy27`` knowing that the correct intepreter will be
used by default - by :user:`stephenfin` (`19 <https://github.com/tox-dev/tox/issues/19>`_)
- Add support to explicitly invoke interpreter directives for environments with
long path lengths. In the event that ``tox`` cannot invoke scripts with a
system-limited shebang (e.x. a Linux host running a Jenkins Pipeline), a user
can set the environment variable ``TOX_LIMITED_SHEBANG`` to workaround the
system's limitation (e.x. ``export TOX_LIMITED_SHEBANG=1``) - by :user:`jdknight` (`794 <https://github.com/tox-dev/tox/issues/794>`_)
- introduce a constants module to be used internally and as experimental API - by :user:`obestwalter` (`798 <https://github.com/tox-dev/tox/issues/798>`_)
- Make ``py2`` and ``py3`` aliases also resolve via ``py`` on windows by :user:`asottile`. This enables the following things:
``tox -e py2`` and ``tox -e py3`` work on windows (they already work on posix); and setting ``basepython=python2`` or ``basepython=python3`` now works on windows. (`856 <https://github.com/tox-dev/tox/issues/856>`_)
- Replace the internal version parsing logic from the not well tested `PEP-386 <https://www.python.org/dev/peps/pep-0386/>`_ parser for the more general `PEP-440 <https://www.python.org/dev/peps/pep-0440/>`_. `packaging >= 17.1 <https://pypi.org/project/packaging/>`_ is now an install dependency by :user:`gaborbernat`. (`860 <https://github.com/tox-dev/tox/issues/860>`_)


Documentation
^^^^^^^^^^^^^

- extend the plugin documentation and make lot of small fixes and improvements - by :user:`obestwalter` (`797 <https://github.com/tox-dev/tox/issues/797>`_)
- tidy up tests - remove unused fixtures, update old cinstructs, etc. - by :user:`obestwalter` (`799 <https://github.com/tox-dev/tox/issues/799>`_)
- Various improvements to documentation: open browser once documentation generation is done, show Github/Travis info on documentation page, remove duplicate header for changelog, generate unreleased news as DRAFT on top of changelog, make the changelog page more compact and readable (width up to 1280px) by :user:`gaborbernat` (`859 <https://github.com/tox-dev/tox/issues/859>`_)


Miscellaneous
^^^^^^^^^^^^^

- filter out unwanted files in package - by :user:`obestwalter` (`754 <https://github.com/tox-dev/tox/issues/754>`_)
- make the already existing implicit API explicit - by :user:`obestwalter` (`800 <https://github.com/tox-dev/tox/issues/800>`_)
- improve tox quickstart and corresponding tests - by :user:`obestwalter` (`801 <https://github.com/tox-dev/tox/issues/801>`_)
- tweak codecov settings via .codecov.yml - by :user:`obestwalter` (`802 <https://github.com/tox-dev/tox/issues/802>`_)

3.0.0

------------------

Bugfixes
^^^^^^^^

- Write directly to stdout buffer if possible to prevent str vs bytes issues -
by asottile (`426 <https://github.com/tox-dev/tox/issues/426>`_)
- fix 672 reporting to json file when skip-missing-interpreters option is used
- by r2dan (`672 <https://github.com/tox-dev/tox/issues/672>`_)
- avoid ``Requested Python version (X.Y) not installed`` stderr output when a
Python environment is looked up using the ``py`` Python launcher on Windows
and the environment is not found installed on the system - by
jurko-gospodnetic (`692 <https://github.com/tox-dev/tox/issues/692>`_)
- Fixed an issue where invocation of tox from the Python package, where
invocation errors (failed actions) occur results in a change in the
sys.stdout stream encoding in Python 3.x. New behaviour is that sys.stdout is
reset back to its original encoding after invocation errors - by tonybaloney
(`723 <https://github.com/tox-dev/tox/issues/723>`_)
- The reading of command output sometimes failed with ``IOError: [Errno 0]
Error`` on Windows, this was fixed by using a simpler method to update the
read buffers. - by fschulze (`727
<https://github.com/tox-dev/tox/issues/727>`_)
- (only affected rc releases) fix up tox.cmdline to be callable without args - by
gaborbernat. (`773 <https://github.com/tox-dev/tox/issues/773>`_)
- (only affected rc releases) Revert breaking change of tox.cmdline not callable
with no args - by gaborbernat. (`773 <https://github.com/tox-dev/tox/issues/773>`_)
- (only affected rc releases) fix 755 by reverting the ``cmdline`` import to the old
location and changing the entry point instead - by fschulze
(`755 <https://github.com/tox-dev/tox/issues/755>`_)


Features
^^^^^^^^

- ``tox`` displays exit code together with ``InvocationError`` - by blueyed
and ederag. (`290 <https://github.com/tox-dev/tox/issues/290>`_)
- Hint for possible signal upon ``InvocationError``, on posix systems - by
ederag and asottile. (`766 <https://github.com/tox-dev/tox/issues/766>`_)
- Add a ``-q`` option to progressively silence tox's output. For each time you
specify ``-q`` to tox, the output provided by tox reduces. This option allows
you to see only your command output without the default verbosity of what tox
is doing. This also counter-acts usage of ``-v``. For example, running ``tox
-v -q ...`` will provide you with the default verbosity. ``tox -vv -q`` is
equivalent to ``tox -v``. By sigmavirus24 (`256
<https://github.com/tox-dev/tox/issues/256>`_)
- add support for negated factor conditions, e.g. ``!dev: production_log`` - by
jurko-gospodnetic (`292 <https://github.com/tox-dev/tox/issues/292>`_)
- Headings like ``installed: <packages>`` will not be printed if there is no
output to display after the :, unless verbosity is set. By cryvate (`601
<https://github.com/tox-dev/tox/issues/601>`_)
- Allow spaces in command line options to pip in deps. Where previously only
``deps=-rreq.txt`` and ``deps=--requirement=req.txt`` worked, now also
``deps=-r req.txt`` and ``deps=--requirement req.txt`` work - by cryvate
(`668 <https://github.com/tox-dev/tox/issues/668>`_)
- drop Python ``2.6`` and ``3.3`` support: ``setuptools`` dropped supporting
these, and as we depend on it we'll follow up with doing the same (use ``tox
<= 2.9.1`` if you still need this support) - by gaborbernat (`679
<https://github.com/tox-dev/tox/issues/679>`_)
- Add tox_runenvreport as a possible plugin, allowing the overriding of the
default behaviour to execute a command to get the installed packages within a
virtual environment - by tonybaloney (`725
<https://github.com/tox-dev/tox/issues/725>`_)
- Forward ``PROCESSOR_ARCHITECTURE`` by default on Windows to fix
``platform.machine()``. (`740 <https://github.com/tox-dev/tox/issues/740>`_)


Documentation
^^^^^^^^^^^^^

- Change favicon to the vector beach ball - by hazalozturk
(`748 <https://github.com/tox-dev/tox/issues/748>`_)
- Change sphinx theme to alabaster and add logo/favicon - by hazalozturk
(`639 <https://github.com/tox-dev/tox/issues/639>`_)


Miscellaneous
^^^^^^^^^^^^^

- Running ``tox`` without a ``setup.py`` now has a more friendly error message
and gives troubleshooting suggestions - by Volcyy.
(`331 <https://github.com/tox-dev/tox/issues/331>`_)
- Fix pycodestyle (formerly pep8) errors E741 (ambiguous variable names, in
this case, 'l's) and remove ignore of this error in tox.ini - by cryvate
(`663 <https://github.com/tox-dev/tox/issues/663>`_)
- touched up ``interpreters.py`` code and added some missing tests for it - by
jurko-gospodnetic (`708 <https://github.com/tox-dev/tox/issues/708>`_)
- The ``PYTHONDONTWRITEBYTECODE`` environment variable is no longer unset - by
stephenfin. (`744 <https://github.com/tox-dev/tox/issues/744>`_)

Links

• PyPI: https://pypi.org/project/tox
• Changelog: https://pyup.io/changelogs/tox/
• Docs: https://tox.readthedocs.org/

[coveralls]

Coverage remained the same at 96.281% when pulling 56db148 on pyup-update-tox-2.9.1-to-3.1.1 into a59bd3f on master.

[pyup-bot]

Closing this in favor of #50