Fixed minor syntax error in Queryset docs
Fixed #22255 -- Added support for specifying re flags in RegexValidator
Bumped version to reflect master is now pre-1.8.
Added stub release notes for 1.8.
Fixed flake8 warnings.
Removed contrib.comments per deprecation timeline.
Removed settings.SEND_BROKEN_LINK_EMAILS per deprecation timeline.
Removed backward compatible shims to rename get_query_set and similar queryset methods.

Also removed the backward compatible shims introduced to rename the
attributes ChangeList.root_query_set and ChangeList.query_set.
Removed django.views.defaults.shortcut and django.conf.urls.shortcut per deprecation timeline.
Removed Model._meta.get_(add|change|delete)_permission methods per deprecation timeline.
Removed fix_ampersands template filter per deprecation timeline.

Also removed related utility functions:
* django.utils.html.fix_ampersands
* django.utils.html.clean_html
Removed settings.CACHE_MIDDLEWARE_ANONYMOUS_ONLY per deprecation timeline.

refs #15201.
Removed reading of old 'django_language' session variable per deprecation timeline.

refs #5789.
Removed PIL compatability layer per deprecation timeline.

refs #19934.
Removed Model._meta.module_name per deprecation timeline.

refs #19689.
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.
Fixed #22299 -- Cleanup wizard temp files when possible.

Thanks to @erikr for the review.