box: Tweak the depth sorting function
box: Tweak the depth sorting function

By changing the depth sorting function we can achieve the same effect as
ClutterGroup but without the costly append+sort.

http://bugzilla.openedhand.com/show_bug.cgi?id=1988

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