Fixed #20235 -- Use self.object_list if object_list not present in get_context_data kwargs.

This is so MultipleObjectMixin can be used in the same way as
SingleObjectMixin.
Merge pull request #1083 from Markush2010/ticket20235

Fixes #20235 - MultipleObjectMixin requires object_list in kwargs
Merge pull request #1084 from erikr/master

Fixed #13546 -- Easier handling of localize field options in ModelForm
Fixed #20269 -- Adapted PostGIS template create script for CentOS/RHEL

Thanks Stephane Benchimol for the report and the initial script and
mfandreas for the patch.
Fixes #19919: get_language_from_request() disregards "en-us" and "en" languages
when matching Accept-Language
Merge pull request #1100 from ambv/issue19919

Fixed #19919: get_language_from_request() disregards en-us and en
Merge pull request #1101 from erikr/master

Fixed argument order for localized_fields to ensure backwards compatibility