python / peps

Further implementation work on the fast locals proxy resulted
in treating the "f_locals" frame storage more as an implicitly
or explicitly updated cache, rather than treating it solely as a
dynamic snapshot.

https://github.com/python/cpython/releases/tag/v3.5.8

* Flake8 fixes

* Use first paragraph of abstract as 'description', and PEP author as 'author'

* Check RSS generation runs with no error

…rs (#2000)

* drop wording about daemon threads in isolated subinterpreters

new threads are not allowed (including daemon threads) implies that the opposite
is true in isolated=False subinterpreters, that new threads are allowed (*excluding* daemon threads)

* Update pep-0554.rst

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>

* `pdb` stores `__return__` and `__exception__`` entries on
  arbitrary frames, so that feature needs to be preserved
* Some fast locals proxy operations will implicitly update the
  underlying shared mapping on the frame
* Anyone explicitly calling `LocalsToFast` is going to want the
  read/write proxy, not any of the read-only options (plus it's
  hard to fit an essay in an error message)
* Remove lingering reference to the removed `PyLocals_RefreshViews()`

Per the announcement on the python-dev mailing list:
https://mail.python.org/archives/list/python-dev@python.org/thread/FQW44V4DZFX4GAGOAMAZAN5KDQXCASDU/

While reading PEP 3104 to understand the ``nonlocal`` keyword, I found the explanation for why an alternative was not chosen to be vague. Further digging revealed an example for why there was a concern that ``.x`` and ``x`` could be used interchangeably. I linked this example as a footnote to save future readers time from digging to find an example. I hope this will increase comprehension of the PEP for future learners.

* PEP 657: addr => addrq

* add underscores

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>

…ifications (#2015)

See #2, #1385 for context. Superseeds #1568.

This is the Sphinx-theming part, building on PR #1930.

### Stylesheets:
- `style.css` - styles
- `mq.css` - media queries

### Jinja2 Templates:
- `page.html` - overarching template

### Javascript:
- `doctools.js` - fixes footnote brackets

### Theme miscellany
- `theme.conf` - sets pygments styles, theme internals

This commit fixes the wording in the comments for failing examples
in the "Backwards Compatibility" section, as suggested by Guido in #2007.