DOC/BLD: update vendored IPython.sphinxext version
updated to commit cc353b25b0fff58e4ed13899df9b3c8153df01d9 from ipython/ipython

xref https://github.com/pandas-dev/pandas/issues/18147, https://github.com/pandas-dev/pandas/pull/19687

Alternative for https://github.com/pandas-dev/pandas/pull/19657 until new release of IPython is out
Hello @jorisvandenbossche! Thanks for submitting the PR.

 - In the file [`doc/sphinxext/ipython_sphinxext/ipython_console_highlighting.py`](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_console_highlighting.py), following are the PEP8 issues :

> [Line 23:1](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_console_highlighting.py#L23): [E305](https://duckduckgo.com/?q=pep8%20E305) expected 2 blank lines after class or function definition, found 1

 - In the file [`doc/sphinxext/ipython_sphinxext/ipython_directive.py`](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py), following are the PEP8 issues :

> [Line 230:80](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L230): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (95 > 79 characters)
> [Line 232:80](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L232): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (80 > 79 characters)
> [Line 353:80](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L353): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (84 > 79 characters)
> [Line 354:65](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L354): [E231](https://duckduckgo.com/?q=pep8%20E231) missing whitespace after ','
> [Line 391:39](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L391): [E261](https://duckduckgo.com/?q=pep8%20E261) at least two spaces before inline comment
> [Line 525:5](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L525): [E303](https://duckduckgo.com/?q=pep8%20E303) too many blank lines (2)
> [Line 538:27](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L538): [E261](https://duckduckgo.com/?q=pep8%20E261) at least two spaces before inline comment
> [Line 585:32](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L585): [E225](https://duckduckgo.com/?q=pep8%20E225) missing whitespace around operator
> [Line 615:44](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L615): [E228](https://duckduckgo.com/?q=pep8%20E228) missing whitespace around modulo operator
> [Line 883:12](https://github.com/pandas-dev/pandas/blob/b9079e9f7aadd75b334f6a90b01de6e21ba6e7f7/doc/sphinxext/ipython_sphinxext/ipython_directive.py#L883): [E713](https://duckduckgo.com/?q=pep8%20E713) test for membership should be 'not in'

 The doc build on travis looks good, and locally as well.

I think the biggest difference in removing/overwriting our own version is that we no longer have the custom `DecodingStringIO` that was introduced in https://github.com/pandas-dev/pandas/pull/6185 to deal with unicode execution results when building the docs (I think this was specifically on Windows, in any case on linux it is working, but would be nice if somebody could  test this on Windows) BTW, I am not going to fix those PEP8 linting warnings, since this would deviate us again from upstream. The linter on travis does not fail on it in any case. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19765?src=pr&el=h1) Report
> Merging [#19765](https://codecov.io/gh/pandas-dev/pandas/pull/19765?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/9df5ab781f903ce00407630aa9db661e3f739bcf?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19765/graphs/tree.svg?height=150&src=pr&token=eZ4WkYLtcO&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/19765?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #19765   +/-   ##
=======================================
  Coverage    91.6%    91.6%           
=======================================
  Files         150      150           
  Lines       48864    48864           
=======================================
  Hits        44763    44763           
  Misses       4101     4101
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.98% <ø> (ø)` | :arrow_up: |
| #single | `41.75% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19765?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19765?src=pr&el=footer). Last update [9df5ab7...b9079e9](https://codecov.io/gh/pandas-dev/pandas/pull/19765?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Merging this, but it would still be good to get feedback from somebody using Windows