Fixed #13408 -- Deprecated silent unpacking exception passing in for template tag.

Thanks peterbe for the suggestion.
Fixed small typo in django-admin.txt

The word 'by' seemed to be missing from the first line of the compilemessages command.
Noted that pip is included with Python 3.4 in Windows install guide.

Thanks CHI Cheng.
Used more specific test assertions.
Fixed #21553 -- Ensured unusable database connections get closed.
Fixed #22401 -- Deprecated regular expression parsing of initial SQL in favor of installing sqlparse.
Fixed #22343 -- Disallowed select_for_update in autocommit mode

The ticket was originally about two failing tests, which are
fixed by putting their queries in transactions.

Thanks Tim Graham for the report, Aymeric Augustin for the fix,
and Simon Charette, Tim Graham & Loïc Bistuer for review.
Documentation fixes for the select_for_update change.

Refs #22343; thanks Tim Graham for the fixes.
Fixed #22412 -- More nuanced advice re template filters and exceptions.

Thanks Tim for review.
Fixed #22195 -- Used constants to define built-in tags for check framework.

Thanks Elvard for the patch.
Fixed #22194 -- Added --list-tags option to check command.

Thanks Elvard for the patch.
Refactored some code in SelectDateWidget.
Fixed #22364 -- Sanitized getpass input in changepassword.

Python 2 getpass on Windows does not accept unicode, even
when containing on ASCII characters. Related #190807.
Fixed #21353 -- Noted that description is ignored for TabularInlines.

Thanks nofinator for the report.
Fixed #22321 -- Wrapped exceptions in _set_autocommit.

Refs #21202.
Fixed #21239 -- Maintained atomicity when closing the connection.

Refs #15802 -- Reverted #7c657b24 as BaseDatabaseWrapper.close() now
has a proper "finally" clause that may need to preserve self.connection.
Fixed #21202 -- Maintained atomicity when the server disconnects.

Thanks intgr for the report.

This commit doesn't include a test because I don't know how to emulate a
database disconnection in a cross-database compatible way.

Also simplified a 'backends' test that was constrained by this problem.
Increased robustness of 58161e4e. Refs #22291.
Fixed #22419 -- Typo in docs/topics/db/multi-db.txt.

Thanks Josh Kupershmidt.
Improved a comment. Thanks intgr for the report.