In a few places I also simplified a few format strings:
-outln("{} item{}", items, items.size() == 1 ? ' ' : 's');
+outln("{} item(s)", items);
In my opinion this is more readable and in some places it incorrectly
wrote '0 item' which is "fixed" now. In other places the placeholder
space looked weird.
Currently only supports setting the foregound and the background colours.
This patch also unifies `foreground_color' and `background_color' used
throughout to a `Format' struct, in hopes of getting more formatting
options one day :P
