libei and gesture events

/me gestures vaguely at everything Oh, hey, this works now? Great! libei 1.7.0 (to be released soon) comes with a new interface: "ei_gestures" which, creatively, will allow for gestures to be sent between a libei client and an EIS implementation (typically: a Wayland compositor). I'm not going to go too deeply into how pinch, swipe and hold gestures work, suffice to say we've had those in libinput…