Honor most of org.gnome.desktop.peripherals.{touchpad,mouse}

This parses most of the above settings hence making touchpads and mice more useful with phoc.

I need to check all the settings work as expected (only checked those i needed right away) but it might be worth an initial look.

This will also be a base for #35 (@francois.techene)

Also makes pointing devices proper gobjects so mostly the tablet realted devices are left to cleanup.

Related: #6 Closes #70 (closed)