Django-admin-sort

- Removed global variables from Javascript namespace.

- Compatible with Django 1.9.
- In the list view, it now is possible to move items to any arbitrary page.

- Changed the namespace from `adminsortable` to `adminsortable2` to allow both this project and
[django-admin-sortable](https://github.com/jazzband/django-admin-sortable) to co-exist in
the same project. This is helpful for projects to transition from one to the other library.
It also allows existing projects\'s migrations which previously relied on django-admin-sortable
to continue to work.

- stabilizer

- re-enable dropdown sorting, finally

- support django 4, drop 1.11
- use github actions for PYPI releases and tests/CI