Removed Django 1.5 upgrade hints for {% url %} tag.

Refs #19280 and Refs #19392.
Fixed #22129 -- Added steps for creating superusers to tutorial.
Fixed #22028 -- Documented that database signals aren't emitted for apps that laack a models module.

Thanks un33k for the suggestion and donjpacheco for the draft patch.
Fixed doc typos.
Fix keyword agument names in RunPython to be positional
Fixed #21948 -- Noted TEMPLATE_LOADERS requirement when overriding admin templates.

Thanks django at patjack.co.uk for the suggestion.
Removed some ReST links to undocumented functions.
Added release note and regression test for refs #21643.

This will be backported to stable/1.6.x along with the original fix.
Fixed spelling mistakes in docs.
Added patch_formats utility for i18n formatting tests
Fixed #22137 -- Made Widget.is_hidden a read-only property

Thanks django at patjack.co.uk for the report and the review.
Fixed #22168 -- Fixed migrations failing on sqlite when column names are SQL keywords

Thanks to trac user fallen_flint for the report and initial patch.
Fixed #15318 -- Added settings for language cookie max-age, path, domain

Introduced a number of settings to configure max-age, path, and domain
for the language cookie: LANGUAGE_COOKIE_AGE, LANGUAGE_COOKIE_PATH and
LANGUAGE_COOKIE_DOMAIN.

Thanks sahid for the suggestion.
Fixed #22130 -- Deprecated fix_ampersands, removed utils.clean_html()
Merge pull request #2382 from erikr/deprecate-fix-ampersands

Fixed #22130 -- Deprecated fix_ampersands and clean_html.
Fixed #22172 -- Allowed index_together to be a single list (rather than list of lists)..

Thanks EmilStenstrom for the suggestion.
Added newline for flake8.
Fixed #22130 -- fixed template_tests/defaultfilters order dependent test failure
Restored aliases for two APIs removed by app-loading.
Merge pull request #2383 from erikr/fix-tests-fix-ampersands-deprecation

Fixed #22130 -- fixed template_tests/defaultfilters order dependent test failure