Important changes:
- UseFixedAuth is now UseAuth and toggles all kinds of authorization and
registration
- UseRegistration is now AllowRegistration to better reflect the meaning
- LimitRegistration is now RegistrationLimit because it's not a boolean,
it's a value (not "limit registration?", but "registration limit is
...")
- registered-users.json is now users.json, because all users are stored
there
- user.AuthUsed is dropped in favor of new cfg.UseAuth which has the
same meaning
I hope I have not forgotten anything.
