Fixed #19477 - Documented generic_inlineformset_factory

Thanks epicserve for the suggestion.
Fixed #19633 - Discouraged use of gunicorn's Django integration.
Remove dup_select_related method.

This undocumented method was used in an old version of the admin, is
totally untested and hails from 2008. Although it's listed in the
"public methods" section, as it's not documented or used I don't think
it needs a deprecation path.

If we think it's useful I'll write some tests/docs for it instead...
Merge pull request #666 from mjtamlyn/dup-select-related

Remove dup_select_related method.
Fixed #19610 - Added enctype note to forms topics doc.

Thanks will@ for the suggestion.
Fixed typo.
Fixed #17416 -- Added widgets argument to inlineformset_factory and modelformset_factory
Fixed #19125 -- The startproject command should validate the name earlier

Thanks Łukasz Rekucki for the report and the patch.
Minor optimization in the static serve view.
More i18n makemessages tests tweaks.
Fixed a typo.
Fixed #19639 - Updated contributing to reflect model choices best practices.

Thanks charettes.
Fixed #6682 -- Made shell's REPL actually execute $PYTHONSTARTUP and `~/.pythonrc.py`.

Also:

* Added a ``--no-startup`` option to disable this behavior. Previous
  logic to try to execute the code in charge of this funcionality was
  flawed (it only tried to do so if the user asked for ipython/bpython
  and they weren't found)
* Expand ``~`` in PYTHONSTARTUP value.

Thanks hekevintran at gmail dot com  for the report and initial patch.

Refs #3381.
Fixed #19577 - Added HTML escaping to admin examples.

Thanks foo@ for the report and Florian Apolloner for the review.
Fixed #19665 -- Ensured proper stderr output for Command.run_from_argv

Thanks Stefan Koegl for the report and Simon Charette for the review.
Patch by Claude for #16084.
Added more shortcuts to i18n docs in index page.
Revert "Patch by Claude for #16084."

This reverts commit 2babab0bb351ff7a13fd23795f5e926a9bf95d22.
Moved has_changed logic from widget to form field

Refs #16612. Thanks Aymeric Augustin for the suggestion.
Fixed #18460 -- Fixed change detection of ReadOnlyPasswordHashField

Thanks jose.sanchez et ezeep.com for the report and Vladimir Ulupov
for the initial patch.