add_cycle_complete_receiver not supported for included animations #96

it seems only animations derived from ColorCycle currently support the callback used by sequence when they complete. I added this code
`def onComplete(sequence):
print("completed sequence", animations.current_animation, sequence)

animations.add_cycle_complete_receiver(onComplete)
`
to the all-animations example, and it is invoked only when the CustomColorChase ends its cycle. outputting:
"completed sequence <CustomColorChase: None> <AnimationSequence: None>"