Django-sortedm2m

-----
* `135`_: Updated README with Jazzband details, and added CONTRIBUTING.md
* `136`_: Dropped support for Python 2.6 and 3.3, and Django < 1.11
* `130`_: Added support for Python 3.7 and Django 2.0 to 2.2
* `130`_: Add support of custom through models (only for Django >= 2.2)
* `138`_: Added coverage reporting

.. _130: https://github.com/jazzband/django-sortedm2m/issues/130
.. _135: https://github.com/jazzband/django-sortedm2m/pull/135
.. _136: https://github.com/jazzband/django-sortedm2m/pull/136
.. _138: https://github.com/jazzband/django-sortedm2m/pull/138

-----

* `101`_: Add support for a custom base class for the many to many intermediate
class. See the README for documentation. Thank you Rohith Asrk for the patch.
* `87`_: Fix ``AlterSortedManyToManyField`` operation to support custom set
``_sort_field_name``.

.. _101: https://github.com/jazzband/django-sortedm2m/pull/101
.. _87: https://github.com/jazzband/django-sortedm2m/issues/87

-----

* `104`_: Add compatibility for Django 1.10 and 1.11!
Thank you Frankie Dintino for the patch.
* `94`_: Add french translation files. Mainly for strings in the admin.
Thanks to ppython for the patch.
* `93`_: Prevent users from accidentally importing and using
``ManyToManyField`` instead of ``SortedManyToManyField`` from ``sortedm2m``.
Thanks Dayne May for the patch.

.. _104: https://github.com/jazzband/django-sortedm2m/pull/104
.. _94: https://github.com/jazzband/django-sortedm2m/pull/94
.. _93: https://github.com/jazzband/django-sortedm2m/pull/93

-----

* `91`_ & `92`_: Fix admin widget, when used with Django 1.10. The add a new
item opup was not closing. Thanks to Tipuch for the patch.

.. _91: https://github.com/jazzband/django-sortedm2m/issues/91
.. _92: https://github.com/jazzband/django-sortedm2m/pull/92

-----

* `80`_ & `83`_: Fix ``SortedMultipleChoiceField.clean`` if the validated
value is ``None``. Thanks to Alex Mannhold for the patch.

.. _80: https://github.com/jazzband/django-sortedm2m/issues/80
.. _83: https://github.com/jazzband/django-sortedm2m/pull/83

-----

* `57`_ & `81`_: Fix add related object popup error prevents operation when
no related objects already exist. Thanks to Vadim Sikora for the fix.

.. _57: https://github.com/jazzband/django-sortedm2m/issue/57
.. _81: https://github.com/jazzband/django-sortedm2m/pull/81