Removed 1.6 release note text regarding password limit length.

This changed was reverted in 5d74853e156105ea02a41f4731346dbe272c2412.
Fixed #21285 -- Fixed E121,E122 pep8 warnings
Fixed #21267 -- Fixed E502 pep8 warnings
Fixed #21268 -- Fixed E303 pep8 warnings
Merge pull request #1768 from alasdairnicol/ticket_21268

Fixed #21268 -- Fixed E303 pep8 warnings
Fixed #21287 -- Fixed E123 pep8 warnings
Fixed bug causing CSRF token not to rotate on login.

Thanks Gavin McQuillan for the report.
Fixed ReST error in 1.6. release notes.
Added a warning regarding session security and subdomains.
Fixed #21212 -- Documented the reverse name for OneToOneField.

Thanks bjb at credil.org for the report.
Cleaned formatting/comments in PasswordResetFormTest
Fixed #21291 -- Ensured inactive users cannot reset their passwords

Thanks kz26 for the report and the suggested fix. Refs #19758.
Removed unused local variables in tests.
Fixed #21283 -- Added support for migrations if models is a package.

Thanks Markus Holtermann for the report.
Added support for serializing class methods. - Refs #21290.

The new handling allows us to do away with the whitelisting that was
required to support date and datetime objects.
Fixed an I18N test class tearDown method.
Fixed #21288 -- Fixed E126 pep8 warnings
Fixed E227 pep8 warnings
Removed some direct settings manipulations in tests; refs #21230.
Fixed #21296 -- Added docs for PostgreSQL and unix domains sockets.