Removed django.forms.widgets.RadioInput per deprecation timeline.

refs #4592.
Removed warning for settings.ADMIN_FOR which has been removed.

refs #21386.
Removed reading of legacy admin popup GET parameter.

refs #20288.
Switched {% cycle %} and {% firstof %} tags to auto-escape their variables per deprecation timeline.

refs #17906.
Fixed broken link in 1.7 release notes due to removal of deprecated code/docs.
Removed django.test.simple and django.test._doctest per deprecation timeline.

refs #17365, #17366, #18727.
Fixed typos in docs (django.contrib.site)
Removed legacy transaction management per the deprecation timeline.
Fixed transaction handling in two management commands.

Previously, when createcachetable and flush operated on non-default
databases, they weren't atomic.
Removed deprecated TRANSACTIONS_MANAGED setting.
Removed useless warning silencing.

If memory serves, the corresponding warning disappeared in Django 1.7.
The cycle and firstof tags no longer raise warnings.

Refs #17906.
Removed django.middleware.doc. Refs #20126.

Small doc changes missed in 66076268.
Removed django.db.backend per deprecation timeline.
Fixed typo in comments.
Removed BaseDatabaseCreation.set_autocommit per deprecation timeline.
Fixed #22307 -- Fixed SpooledTemporaryFile bug in File class.

Added condition to prevent checking the existence of a file name of a
file like object when the name attribute is None. This is necessary
because a SpooledTemporaryFile won't exist on the file system or have a
name until it has reached its max_size. Also added tests.
Removed hard-coded help_text for ManyToManyFields that use a SelectMultiple widget

Per deprecation timeline; refs #9321.
Removed warning for Widget.is_hidden property.

refs #22137.
Removed backwards compatibility code to call field.widget._has_changed()

This logic should be moved to field._has_changed() as described
in ebb504db692cac496f4f45762d1d14644c9fa6f - refs #16612.