Fixed #20321 -- Added missing key name in MergeDict KeyError message

Thanks mark.harviston et gmail.com for the report.
Fixed #18336 -- Doubled request_queue_size.

This reduces random failures to load static files with Google Chrome.
Pointed to the docs version switcher in tutorial 1.

Refs #20324. Thanks dwisehart for the suggestion.
Fixed #18986 -- Improved error message for missing files

in CachedStaticFilesStorage. Thanks zyegfryed for his work on the patch.
Tested that get_or_create raises IntegrityError.

It used to raise "DatabaseError: no such savepoint" with the old
transaction management. Closes #15117.
Corrected "it's" to "its" when used possessively.

Fixed #20327.
Fixed #20330 -- Normalized spelling of "web server".

Thanks Baptiste Mispelon for the report.
Fix two typos in database transactions docs
Merge pull request #1034 from infraredgirl/master

Fix two typos in database transactions docs
Fixed #20336 -- Removed obsolete paragraph from the docs.

Thanks Baptiste Mispelon.
Fixed #19252 -- Added support for wheel packages.

Signed-off-by: Jannis Leidel <jannis@leidel.info>
Fixed test failures introduced in a5becad9094e5c5403b692b9a7b3a6ffaabf64a3.
Fixed #20338 - Document FQDN behavior with ALLOWED_HOSTS
Updated translation templates and removed en translations

"en" translations have been mistakenly committed in 87cc3da81.
Added myself to the committers list.
Used ngettext in a formsets error message

Several languages will distinctly translate '%d or fewer forms'
depending on the variable.
Systematically imported wraps from functools
Fixed #18351 -- Added X-Robots-Tag header to sitemaps

Thanks Michael Lissner for the report and initial patch, and
Tom Mortimer-Jones for working on the patch.
One more changed import location of wraps
Fixed a regression introduced in 9f7a01ef2bed8c0395a970286e8f87fd7d344b3b.