examples/threads: Modernize code
examples/threads: Modernize code

Drop the usage of behaviours and alphas, and use transitions and
implicit animations instead.

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