Enabled makemessages to support several translation directories

Thanks Rémy Hubscher, Ramiro Morales, Unai Zalakain and
Tim Graham for the reviews.
Also fixes #16084.
Closed file after reading pot file

Faulty line was introduced in 50a8ab7cd1.
Fixed comment typos.
Documented the house style for gender neutral pronouns.
Removed gender-based pronouns per [c0a2daad78].
Fixed #21358 -- Allowed runserver on non-English locales

Thanks svartalf for the report.
Refs #21230 -- removed direct settings manipulation from template tests
Fixed #21535 -- Fixed password hash iteration upgrade.

Thanks jared_mess for the report.