[animation] add varargs support for signal::completed
[animation] add varargs support for signal::completed

Added support for registering a handler for the completed signal
directly amongst the varargs making it easier to attach code
to be executed when animations complete.

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