Fixed #20774 -- Mention the new django-localflavor app as a replacement for the contrib app.
Allowed overriding variables in docs/Makefile.
Misc doc cleanups.
Fixed #18213 -- Allowed empty fixtures (emit a warning rather than raising an exception).
Fixed #20817 -- Added html_message parameter to django.core.mail.send_mail()
Deprecated django.utils.importlib

This was a shim for pre-Python 2.7 support.
Add utf-8 preamble to admin_scripts temp settings file

As some settings are copied from current user settings, we cannot
be sure the characters are pure ascii.
Fixed #14850 -- Cleaned up duplicate code in admin formset handling.

Thanks apollo13 for the report and review.
Fixed #19617 -- Refactored form metaclasses to support more inheritance scenarios.
POC: Removed support for Fields on plain objects and added support for Field shadowing