message: Started animation on mount
  Component did update doesn't run first render so started animation for safety. Don't think it's needed because animation shouldn't run on startup but ensures that it goes through the normal logic and sets rest and progress correctly
diff: @@ -16,6 +16,9 @@ class Motion<T> extends React.Component<MotionProps<T>, any> {
  var {items, moving} = Motion.move(tick, prevItems, props);
  return {items, restart: moving};
  }
  + componentDidMount() {
  + this.animateId = requestAnimationFrame(this.animate);
  + }
  componentDidUpdate() {
  if (!this.animateId && this.state.restart)
  this.animateId = requestAnimationFrame(this.animate);
  