cookbook: Handle all possible mouse scroll directions
cookbook: Handle all possible mouse scroll directions

Added empty cases for MOUSE_SCROLL_LEFT and MOUSE_SCROLL_RIGHT
to the scroll-event signal handler in the example code.

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