Fixed #19119 -- Corrected default date input formats in docs

Thanks henrik@aisti.fi for the report.
Added ref to format localization in Date[Time]Field docs

Thanks henrik@aisti.fi for the suggestion in #19119.
Fixed #18484 -- Removed the div around the csrf token input
Added 'groups' to UserAdmin.filter_horizontal

Is there some reason it's not there already?

Our list of groups is very cumbersome to use with the standard widget.
Fixed #16479 - Forms generated from formsets use ErrorList instead of supplied error_class

Patch with tests from charettes, updated.
Added release note about removed div around csrf token

Refs #18484. Thanks Simon Charette for the suggestion.
Replaced mentions of Subversion by Git in docs
Build context strings out of [u|n]gettext

The context strings in [n]pgettext functions should not be marked
themselves for translation.
Updated base translation files
Allow reversed iteration over SortedDict.

Iterators cannot be reversed easily without this method.
Updated Transifex base url
Added DeprecationWarning for django.contrib.localflavor.
Note this is DeprecationWarning instead of PendingDeprecationWarning because we've decided
to accelerate this particular deprecation.
Merge pull request #436 from ddbeck/patch-1

Removed heteronormativity from coding style doc
Fixed #15753 -- Cleared cache between sitemaps tests

When caching was activated, test_simple_sitemap would fail
because the test result was fetched from cache.
Thanks lucho for the initial patch and krzysiumed@gmail.com for
the review.
Added tests for reversed iteration over SortedDict.
Added docs link to new third-party Lithuanian localflavor
Fixed assertXMLEqual when first node was a comment
Made use of assertXMLEqual in sitemaps tests
Fixed #18715 - Refactored tutorial 3. Thank-you Daniel Greenfeld!
Fixed #10936 - Tempered recommendation of SQLite - thanks Karen Tracey for the feedback.