[animation] Do not leak timelines
[animation] Do not leak timelines

The timeline created when calling set_timeline(NULL) is referenced
even though we implicitly own it. When the Animation is destroyed,
the timeline is then leaked.

Thanks to: Richard Heatley <richard.heatley@starleaf.com>

Fixes bug:

  http://bugzilla.openedhand.com/show_bug.cgi?id=1548

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