Fixed #21606 -- Fixed default_lat and default_lon override in OSMWidget
Allowed running GIS form tests that don't require spatial database
Fixed link text for "Testing in Django" in tutorial 5.
Removed usage of to-be-deprecated ADMIN_FOR setting in contributing docs
Fixed #21614 -- improved docs on configuring email for development.
Fixed E127 pep8 warnings.
Clarifed table rewrites in migration docs.

Small nitpicks. All column-related ALTER TABLE commands take an
exclusive table lock in PostgreSQL. The difference is that adding a
column without default doesn't cause a table rewrite, so the lock is
held only for a short time.

The time taken is more accurately proportional to table size, not row
count.
Fixed #21250 -- Made HTTP auth user header configurable in tests

Currently, if the authentication mechanism uses a custom HTTP header
and not REMOTE_USER, it is not easy to test. This commit modifies
remote user tests in order to make them more generic.
Revert "Allowed running GIS form tests that don't require spatial database"

This reverts commit 07fe0bf3f4a49a734f83f5ea30130449dacf9660.
This was not working properly on system without geos library
installed.
Fixed #21539 -- Added example of modelformset_factory's form argument
Added internal link to i18n documentation.