Django-unicorn

- Support calling functions in JavaScript modules
- Fix: use `unicorn:db` without a `unicorn:model` in the same element

- Support custom CSRF headers set with [CSRF_HEADER_NAME](https://docs.djangoproject.com/en/stable/ref/settings/#csrf-header-name) setting.

- Performance enhancement that returns a 304 HTTP status code when an action happens, but the content doesn't change.
- Add `unicorn:ignore` attribute to prevent an element from being morphed (useful when using `Unicorn` with libraries like `Select2` that change the DOM).
- Add support for passing arguments to `Unicorn.call`.
- Bug fix when attempting to cache component views that utilize the `db_model` decorator.

- Use Django cache for storing component state when available
- Add support for Django 2.2.x

- Add backported `dataclasses` as a dependency for Python 3.6.

- Bug: Prevent disabled polls from firing at all.
- Handle serializing `Decimal` fields.
- Use type hints to cast fields to primitive Python types if possible.
- Support `dataclass` field type.