The new jellyfin_login and admin_only allow anyone use their username and
password from jellyfin to login to the admin page, and restrict this to jellyfin
admins only, respectively.
The admin page now has the option to send an invite to an email address.
Since there are now two email types (invites and pw resets), the new
sections have been added to config.ini, and email_template and
email_plaintext have been renamed to email_html and email_text
respectively.
Fixed an issue where some criteria on the form page wouldn't change to
red or green when one set one of them to 0 in the config. Also added a
lowercase option.
Password validation added, configurable under the [password_validation]
section in config.ini. Each criterion is displayed next to the form, in
red or green depending on whether the password passes it. form.html now
looks different because of it, whether it is enabled or disabled. An
error message is now displayed if the user already exists.
