[1.7.x] Fixed #22924 -- Added a note about MEDIA_URL in templates.

Thanks raphael.herouart at gmail.com

Backport of 814bcc3395 from master
[1.7.x] Fixed #22915 -- Document backward incompatible changes in the ValidationError constructor.

This patch also fixes update_error_dict to better handle the use case described
in this ticket, previously the type of the provided container could be lost in
some conditions.

Thanks Russell Keith-Magee for the report and Tim Graham for review.

Backport of eb7df6b8d7 from master
[1.7.x] Ensured bound field renders as unicode safe data

Refs #22950.
Backport of 920904921 from master.
[1.7.x] Fixed #22960: Bad handling of relations as PKs in autodetector
[1.7.x] Fixed #22943 -- Correctly serialize compiled regexes.

Thanks to antialiasis at gmail dot com for the patch.
[1.7.x] Added a space before explanation of "Invalid HTTP_HOST header: ..."

Backport of fff7b507ef from master
[1.7.x] Updated tests per previous commit.

Backport of 86c74eacd6 from master
[1.7.x] Fixed flake8 indentation.

Backport of ab431fbd4f from master
[1.7.x] Fixed various minor doc typos / references.

Backport of 67f9f385aa from master
[1.7.x] Document --fake and --list on migrate command
[1.7.x] Fixed #22906 -- Added a more helpful repr to migrations' ModelState.

Thanks Collin Anderson for the report and original patch.

Backport of 2572c07cc6 from master
[1.7.x] Fixed pyinotify performance regression in 15f82c7011

Refs #9722. Thanks Tim Graham for the review.
Backport of 6d302f639 from master.
[1.7.x] Fixed #22966 -- Clarified which release notes appear for each doc version.

Thanks haimunt at yahoo.com for the suggestion.

Backport of e6b3d6c22f from master
[1.7.x] Fixed a few PEP8 errors in settings doc.

Backport of 2c1384fbac from master
[1.7.x] Fixed #22942 -- Noted that __init__.py files are required for management command detection.

Thanks Diego Cerdán for the suggestion.

Backport of 54546cee88 from master
[1.7.x] Fixed #22909 -- Removed camelCasing in some tests.

Thanks brylie.

Backport of 89b9e6e5d6 from master
[1.7.x] Fixed flake8 errors.

Backport of fddd95254e from master
[1.7.x] Removed unnecessary directory in dispatch tests.

Backport of 136a3ffe21 from master
[1.7.x] Renamed an admin_views test to fix ordering issue.

test_i18n_language_non_english_fallback fails if run after
test_L10N_deactivated; the tests can be run in any order after
a5f6cbce07b5f3ab48d931e3fd1883c757fb9b45 but this commit is not
in stable/1.7.x.