Use clutter_container_find_child_by_id() when picking
Use clutter_container_find_child_by_id() when picking

ClutterStage now uses the newly added clutter_container_find_child_by_id()
function to find the right child in the scenegraph, using the picking id.

This fixes the test-boxes test case.

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