message: Initialised progress to 1 if complete
  Saves a couple of renders/moves on start up. Let rest get set to true in the next iteration so that onRest gets called
diff: @@ -67,9 +67,10 @@ class Motion<T> extends React.Component<MotionProps<T>, any> {
  .filter(item => !itemsByKey[getKey(item)])
  .map(item => {
  var index = dataByKey[getKey(item)].index;
  - var newItem: any = {key: getKey(item), data: item, progress, tick, rest: false, index};
  + var newItem: any = {key: getKey(item), data: item, tick, rest: false, index};
  newItem.start = newItem.style = enter(item);
  newItem.end = update(item);
  + newItem.progress = Motion.areEqual(newItem.start, newItem.end) ? 1 : 0;
  return newItem;
  })
  )
  