The order and way include macros were structured was chaotic, with no
real common thread between files. Try to tidy up the mess with some
common scheme, to make things look less messy.
Make the device <-> seat association permanent, and move it into
MetaWaylandInputDevice. A device will never be disassociated with a
seat, so there is no point in unsetting it.
https://bugzilla.gnome.org/show_bug.cgi?id=771305
Remove our own copy of the pointer gestures protocol, and us the one
installed by wayland-protocols. This also means the new fixed unstable
naming conventions are used for the new version of the protocol, which
is reflected in the change. No functional changes were made, it is only
a rename.
https://bugzilla.gnome.org/show_bug.cgi?id=758633
