[event] Extend KeyEvent for multi-input support
[event] Extend KeyEvent for multi-input support

Key events can come from different input devices, so they need a
ClutterInputDevice member like the pointer-related events. This
field is reserved for future use.

jigpu/clutter,spatulasnout/clutter,djdeath/clutter-multithreaded,collects/clutter,nobled/clutter,jigpu/clutter,Distrotech/clutter,kerrickstaley/clutter-vala,spatulasnout/clutter,djdeath/clutter,Distrotech/clutter,collects/clutter,djdeath/clutter-multithreaded,djdeath/clutter-multithreaded,djdeath/clutter-android,rkudiyarov/clutter_osx,jigpu/clutter,nobled/clutter,GNOME/clutter,collects/clutter,djdeath/clutter-multithreaded,rkudiyarov/clutter_osx,collects/clutter,jigpu/clutter,heysion/clutter-clone,djdeath/clutter,djdeath/clutter-android,ebassi/clutter,djdeath/clutter,dlespiau/clutter,GNOME/clutter,Distrotech/clutter,rkudiyarov/clutter_osx,ebassi/clutter,GNOME/clutter,ebassi/clutter,spatulasnout/clutter,GNOME/clutter,djdeath/clutter,djdeath/clutter-android,tardyp/clutter,tardyp/clutter,djdeath/clutter-android,nobled/clutter,GNOME/clutter,djdeath/clutter,kerrickstaley/clutter-vala,djdeath/clutter,ebassi/clutter,spatulasnout/clutter,djdeath/clutter-android,kerrickstaley/clutter-vala,kerrickstaley/clutter-vala,jigpu/clutter,tardyp/clutter,dlespiau/clutter,dlespiau/clutter,collects/clutter,Distrotech/clutter,heysion/clutter-clone,Distrotech/clutter,rkudiyarov/clutter_osx,heysion/clutter-clone,jigpu/clutter,ebassi/clutter,heysion/clutter-clone,heysion/clutter-clone,Distrotech/clutter,spatulasnout/clutter