Conflicts:
- `app/models/form/admin_settings.rb`:
Upstream added the notion of overriden settings, while we had extra code for
pseudo-settings (only used to combine flavour and skin in a single select
field).
Ported upstream changes.
- `config/i18n-tasks.yml`:
Upstream added `simple_form.overridden` to `ignore_unused`,
we had `simple_form.glitch_only`.
Added `simple_form.glitch_only` as well.