layout, box: Clean up
layout, box: Clean up

* Use g_list_foreach() instead of iterating over the list inside
  the destruction sequence, since we are causing the widgets to be
  implicitly removed from the list via the destroy() call.

* Use g_signal_connect_swapped() and spare us from a callback.

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