Fixed #16319 -- added SuccessMessageMixin to contrib.messages

Thanks martinogden for the initial patch and d1ffuz0r for tests.
Reordered AUTHORS in last name alphabetic order
Revert "Fixed 19895 -- Made second iteration over invalid queryset raise an exception too"

This reverts commit 2cd0edaa477b327024e4007c8eaf46646dcd0f21.
This commit was the cause of a memory leak. See ticket for more details.
Thanks Anssi Kääriäinen for identifying the source of the bug.
Fixed #19972 -- Fixed overflow issue in admin changelist pages.

Thanks to loic84 for the report and patch.
Fixed #20096 -- Added link to the Greek localflavor app
Added tests for already fixed #20101

The ticket dealt with a case where one query had .exclude() that
produced a subquery, the other query had a join to the same model that
was subqueried in the first query. This was already fixed in master, so
only test added.
Fixed #18972 -- Refactored bundled wsgi server's chunking algorithm.

Thanks to amosonn at yahoo.com for the report, @doda for the initial patch and
@datagrok for the revamped logic and test case.
Removed unused import
Fixed #18839 - Field.__init__() now calls super().
Fixed #20084 -- Provided option to validate formset max_num on server.

This is provided as a new "validate_max" formset_factory option defaulting to
False, since the non-validating behavior of max_num is longstanding, and there
is certainly code relying on it. (In fact, even the Django admin relies on it
for the case where there are more existing inlines than the given max_num). It
may be that at some point we want to deprecate validate_max=False and
eventually remove the option, but this commit takes no steps in that direction.

This also fixes the DoS-prevention absolute_max enforcement so that it causes a
form validation error rather than an IndexError, and ensures that absolute_max
is always 1000 more than max_num, to prevent surprising changes in behavior
with max_num close to absolute_max.

Lastly, this commit fixes the previous inconsistency between a regular formset
and a model formset in the precedence of max_num and initial data. Previously
in a regular formset, if the provided initial data was longer than max_num, it
was truncated; in a model formset, all initial forms would be displayed
regardless of max_num. Now regular formsets are the same as model formsets; all
initial forms are displayed, even if more than max_num. (But if validate_max is
True, submitting these forms will result in a "too many forms" validation
error!) This combination of behaviors was chosen to keep the max_num validation
simple and consistent, and avoid silent data loss due to truncation of initial
data.

Thanks to Preston for discussion of the design choices.
Docs template name mistake

change_list_request.html doesn't exist, it's named  change_list_results.html
Fixed #17935 - Clarified intro of topics/files.txt.

Thanks guettli for the suggestion.
Fixed #20094 - Be more careful when checking for Iterator

Python 2.6 has some different behaviour when checking
isinstance(foo, collections.Iterator).
Fixed #20108 -- Fixed filepath_to_uri decoding error

This was a regression due to unicode_literals usage. Thanks Ivan
Virabyan for the report and the initial patch.
Merge pull request #935 from tomviner/master

Docs template name typo
Added missing markup to docs.
Fixed #16350 -- Forced capitalization in template.

This improves rendering in some foreign languages.