Remove unnecessary and problematic parent class from SuccessMessageMixin

refs #16319, thanks to bmispelon for the catch
Replaced an antiquated pattern.

Thanks Lennart Regebro for pointing it out.
Modernize the CSRF migration helper.

Thanks Lennart Regebro for spotting that code.
Fix up company link.
Fixed #20427 -- Moved a variable initialization in storage.py

This is fixing commit 4e70ad11d2. Thanks mattias at elements.nl
for the report and Baptiste Mispelon for identifying the faulty
commit.
Tidy up some of the transaction documentation.
Finally add myself to the committers list
Corrected documentation on the constructor arguments of MultiPartParser
Merge branch 'master' into schema-alteration
Reorganize committers list chronologically.

This completes the removal of the distinction between core devs and
specialists.

Patch by Simon Meers.
Merge pull request #1082 from hydrogen18/master

Fixed some documentation on the MultiPartParser
Fixed #20422 -- Applied makemessage's --ignore patterns to full path

Fix makemessage's --ignore patterns being applied to the full path
instead of the file name. Thanks to nnseva for the report and the
original patch.
Turn SchemaEditor into a context manager
More conversion to a ContextManager schema_editor
Fixed #20411 -- Don't let invalid referers blow up CSRF same origin checks.

Thanks to edevil for the report and saz for the patch.
Fixed #20356 -- Prevented crash when HTTP_REFERER contains non-ascii

Thanks srusskih for the report and Aymeric Augustin for the review.
Fixed #20294 -- Documented context processors in TemplateResponseMixin.
Fixed #20408 -- Clarified that values_list() doesn't return a list.

Thanks marktranchant, bmispelon, and alextreme.
Added test for multipart, non form-data POST.

Closes #9054. The bug itself is no longer present.
#20432: Fix for GroupAdmin test