Properly manage timeline refcounting in clutter_animation_set_timeline()
Properly manage timeline refcounting in clutter_animation_set_timeline()

This patch fixes clutter to not crash when multiple animations share
the same timeline and the actors are explicitly destroyed before
the timeline completes (bug 672890)

collects/clutter,kerrickstaley/clutter-vala,heysion/clutter-clone,GNOME/clutter,jigpu/clutter,kerrickstaley/clutter-vala,Distrotech/clutter,Distrotech/clutter,ebassi/clutter,djdeath/clutter,collects/clutter,djdeath/clutter,collects/clutter,ebassi/clutter,kerrickstaley/clutter-vala,heysion/clutter-clone,djdeath/clutter,jigpu/clutter,djdeath/clutter,djdeath/clutter-android,ebassi/clutter,heysion/clutter-clone,kerrickstaley/clutter-vala,jigpu/clutter,djdeath/clutter-android,jigpu/clutter,heysion/clutter-clone,GNOME/clutter,GNOME/clutter,ebassi/clutter,collects/clutter,ebassi/clutter,GNOME/clutter,heysion/clutter-clone,djdeath/clutter,GNOME/clutter,collects/clutter,Distrotech/clutter,djdeath/clutter-android,Distrotech/clutter,djdeath/clutter-android,djdeath/clutter-android,Distrotech/clutter,djdeath/clutter,Distrotech/clutter,jigpu/clutter,jigpu/clutter