[1.6.x] Re-added link to SQLite notes from DB section of install doc.

67f5dffbec from master.
[1.6.x] Refs #21197 -- Clarified upgrade check message.

Thanks to Carl and Shai for the discussion.

Backport of 8ff4303 from master.
[1.6.x] Fixed #21164 -- Added documentation for issue with test users.

The package renaming restores the older package names (which were also the
documented package names). This doesn't affect test discovery because the
module in question doesn't contain any tests.

Thanks to Carl for the design discussion.

Backport of ddb5385 from master.
[1.6.x] Fix grammatical errors in email documentation

Backport of 43f213e475 from master
[1.6.x] Fixed #21243 -- Corrected exception message in multiple database tests.

Thanks to vajrasky for the report and patch.

Backport of a971d19 from trunk.
[1.6.x] Fixed grammar/typos in auth customization docs

Backport of 1b9c72fc4f from master.
[1.6.x] Updated auth translation template
[1.6.x] Small improvements to docs/topics/db/models.txt

Backport of 695bc0d191 from master
[1.6.x] Minor edits to docs/topics/db/queries.txt.

Backport of 8bfc7cc64c from master
[1.6.x] Fixed #15582 -- Documented how TransactionTestCase.multi_db affects fixtures.

Thanks slinkp for the suggestion.

Backport of dd839a2dfd from master
[1.6.x] Forms docs: More emphasis in 'id'  value customizability.

18ea1c473b form master.
[1.6.x] Fixed #19560 -- Identified field in warning for naive datetime.

Thanks gcc for the report and vajrasky for the patch.

Backport of 570d9c2678d6cc564f9c70138554af8f7ce9ec49 from master.
Fixed #21198 -- Prevented invalid use of @python_2_unicode_compatible.

Thanks jpic for the report and chmodas for working on a patch.

Reverts 2ea80b94. Refs #19362.

Conflicts:
	tests/utils_tests/test_encoding.py
[1.6.x] Fixed #21256 -- Error in datetime_safe.datetime.combine.

Backport of d9b6fb8 from master
[1.6.x] Imported custom user classes in tests depending on it

Without those imports, affected test files cannot be run
independently. Refs #21164.

Backport of ef22d512b5 from master.
[1.6.x] Fixed #21027 -- Updated tutorial 5 docs to link to management shell command page.

Backport of 13ddf0e002 from master
[1.6.x] Fixed #21264 -- Incorrect RST usage in docs

Backport of 8fc63087f6 from master
[1.6.x] Fixed #21210 -- Documented when runserver doesn't auto-restart.

Thanks gergely at polonkai.eu for the suggestion.

Backport of 9b7d38ed5a from master
[1.6.x] Clarfied the ModelForm docs with respect to generated vs. declared fields.

The ModelForm docs suggested that fields defined declaratively override
default fields generated from the form Meta.

This is conceptually wrong, especially with inheritance in mind. Meta is
usually defined on the topmost ModelForm subclass, while fields can come
from anywhere in the MRO, especially base classes; therefore we suggested
that something defined in a base class override something from a subclass.

This patch rephrases the docs around the idea that Meta is used to generate
*missing* fields.

Refs #8620, #19617.

Thanks @mjtamlyn and @timgraham for the review.

Backport of 54cd930baf from master
[1.6.x] Fixed #20962 -- Documented that template tag render() may raise exceptions.

Thanks Keryn Knight for the report.

Backport of e077224f4a from master