* Change color of 'please log in' message

* Set placeholder on ORCID field

* Set title and pattern on ORCID field

* Update CHANGELOG

* One fewer .save() in user creation

* enable_register → registration_enabled

* Use FormView as base for RegisterView

* Fix NULL constraint in HeliportGroup creation

* Add ORCID validation

* Fix bug in clean_X functions

They have to return the cleaned value.

* Fix type annotations for Python 3.8

* Fix tests

* Move RegisterView into views.user

* Add type annotations

* Rename template heliport_login → login

* Create common base template for login and register

* Align login and register template

They now look the same except for the form.

* Add missing docstring

* Replace some style attrs with classes

* Use .form-text for all errors

* Update login UI to match registration form

* Remove rendering of obsolete message variable

* RegisterView based on new RegistrationForm

* Simplify login UI

* Login UI based on Django form

* Install django-widget-tweaks

This allows us to alter rendering of Django forms using template tags
rather than in Python code.

* Add back messages to login page

* Replace LoginView with Django built-in LoginView

* Use user_logged_in signal instead of post_save

* Update HELIPORT user/group in post_save handler

This is the way suggested in Django's custom auth guide and it will
allow us to get rid of the custom LoginView.

See: https://docs.djangoproject.com/en/4.2/topics/auth/customizing/#extending-the-existing-user-model

* Don't pass backend to login function

As explained in the docs, it can be determined automatically from the
`user.backend` attribute.

See: https://docs.djangoproject.com/en/4.2/topics/auth/default/#selecting-the-authentication-backend

This also means that the `auth_backend` attribute on the
`UserInformationManager` is not needed.

* Remove is_login_page distinction

This was used to change the behaviour of the navbar HELIPORT logo. On
normal pages, it would lead users to /project/list/, on the login page
it would lead users to / which would return a redirect to
/project/list/, thus making the distinction unnecessary.