tools (common/template): theme settings with possibility to disable default fallback for CSS: - themes can now have a `settings.json` file at their root to modify the renderer behaviour - the `css_default_fallback` boolean (true by default) can be used to disable the fallback mechanism when CSS files are checked. Useful when a theme doesn't follow the CSS naming of default theme. - introduced some type hints

[D-BUS Service]
Name=org.salutatoi.SAT
Exec=sat