Libinput is done

thanks, I'll have a look.

note that libinput is a bit special, it's not a generic library that we expect applications to use. there is a very limited number of expected libinput users (most Wayland compositors and the xorg driver) and a few others like research projects and PoCs. but compared to gegl it's not a generic user-facing library, so the documentation requirements are a bit different (i.e. we can ignore most of the entry-level stuff)