- The configuration for writing the hostname (to /etc/hostname,
to /etc/hosts and possibly to systemd-hostname) is read-only,
because it comes from the config file and won't change after.
- add the "reuse user password for root" setting to Config,
make the UI page follow that setting.
- add the require-strong-password default and toggle settings to
Config; this is not well-checked yet.
On the widget / UI side, connect checkboxes only if they are
visible; refactor reuse-user-password-for-root settings.
- drop groups from the viewstep
- note that the Config object should also be in charge of creating
Jobs (but then the de-tangling needs to be completed)
- add tests of default groups loading
Doesn't compile because QRegExpValidator is a gui thing.
