Update ipython to 6.4.0

[pyup-bot]

This PR updates ipython from 5.4.1 to 6.4.0.

Changelog

6.2.1

None

6.2.0

None

6.1.0

None

6.0.0

None

6.0.0rc1

None

rel-3.0.0
See the [release notes](http://ipython.org/ipython-doc/3/whatsnew/version3.htmlrelease-3-0) for what's new.

or get it with pip:


pip install --upgrade "ipython[all]"


DO NOT download from the "Source code" links below. They are missing git submodules, and won't work.


rel-2.4.1


rel-2.1.0
bugfix release for IPython 2.0. See the [list of backported fixes](http://ipython.org/ipython-doc/2/whatsnew/github-stats-2.0.html).


rel-1.2.1
Bugfix release for Python 2.6 and 3.4.

[What's new in 1.2](http://ipython.org/ipython-doc/1/whatsnew/github-stats-1.0.htmlissues-closed-in-1-2)


rel-1.2.0
IPython 1.2.0 mostly bugfix release

For release notes, see [what's new](http://ipython.org/ipython-doc/rel-1.2.0/whatsnew/github-stats-1.0.html).


rel-1.1.0

Links

• PyPI: https://pypi.org/project/ipython
• Changelog: https://pyup.io/changelogs/ipython/
• Homepage: https://ipython.org

[pyup-bot]

Closing this in favor of #276