Fixed #14930 -- values_list() failure on qs ordered by extra column

Thanks lsaffre for the report and simon29, vicould, and Florian Hahn
for the patch.

Some changes done by committer.
Fixed broken reference in documentation.
Fixed MySQL failing test introduced by c86a9b6
Merge pull request #1282 from loic/ticket6903

Fixed failing test on MySQL since c86a9b6
Removed several unused imports.
Fixed #20288 -- Fixed inconsistency in the naming of the popup GET parameter.

Thanks to Keryn Knight for the initial report and reviews,
and to tomask for the original patch.
Itty bitty typo fix.

"deletes" was missing it's last e.
Merge pull request #1287 from mintchaos/patch-1

Itty bitty typo fix.
Fixed #20486 -- Ensure that file_move_safe raises an error if the destination already exists.

Thanks to kux for the report, and Russ Webber for the patch.
Fixed #20632 -- Fixed {{ docs_version }} in project template
Modified tutorial 3 to use RequestContext in place of Context.
Fixed error in last commit. Thanks Simon Charette.
Fixed #20630 -- Removed `maxlength` attribute from `NumberInput`.

This attribute is only allowed on inputs of type "text", "search", "url",
"tel", "email", or "password".

Thanks to yoyoma for the report and @bmispelon for the review.
Fixed #19319 -- Updated example httpd.conf for Apache 2.4

Thanks colinnkeenan@ for the report.
Fixed #20290 -- Allow override_settings to be nested

Refactored override_settings to store the underlying settings._wrapped
value seen at runtime, not instantiation time.
Fixed #20612 -- Fixed incorrect wording in CBV documentation

Thanks to ndokos for the report.
Fixed #19881 -- Documented that get_next/previous_by_FOO uses default manager.
Fixed #20634 - Corrected doc mistake re: staticfiles finders strategy.

Thanks claudep for the catch and bmispelon for the research.
Fixed 17478 -- Allowed queryset overriding in BaseModelFormSet init

BaseModelFormSet.forms is now a cached property instead of being
populated in the __init__ method. This behaviour also matches an
example in the documentation.
Thanks Thomasz Swiderski for the report and Simon Charette for the
review.
Fixed #18872 -- Added prefix to FormMixin

Thanks @ibustama for the initial patch and dragonsnaker for opening the
report.