Conflicts:
- `app/lib/themes.rb`
- `app/views/layouts/application.html.haml`
- `app/views/layouts/embedded.html.haml`
- `app/views/layouts/error.html.haml`
- `config/settings.yml`
All these conflicts are because glitch-soc and upstream have different theming
systems and upstream changed a few things to have dynamic theme selection based
on system settings.
Conflicts were solved to take that into account, and `current_theme` has been
changed in the process to return a tuple of `[flavour, skin]` to be used in
the `theme_style_tags` helper.
Packs are now loaded from views, just like upstream, and are
identified by their filenames. The definition of `theme.yml` has
changed as such:
- `pack_directory` is now required
- `pack` is now unused
- `signed_in_preload` has been introduced
Remove the `fallback` property and do not fallback to using another flavour
when a pack is not available in the selected flavour.
Flavours should define all packs, and should they wish to piggy-back on
another one, they can import that other one's pack explicitly instead.
