message: Concatenated crumbs and nextCrumb
  Means sceneContexts is an array of crumbs and avoids the cast
diff: @@ -45,18 +45,18 @@ class SceneNavigator extends React.Component<any, any> {
  );
  }
  render() {
  - var {oldState, oldData, state, data, url, crumbs} = this.getStateNavigator().stateContext;
  + var {oldState, oldData, state, data, crumbs, nextCrumb} = this.getStateNavigator().stateContext;
  if (!state)
  return null;
  var {unmountedStyle, mountedStyle, style} = this.props;
  - var sceneContexts = (crumbs as [any]).concat({state, data, url, mount: true});
  + var sceneContexts = crumbs.concat(nextCrumb);
  return (
  <TransitionMotion
  willEnter={() => getStyle(unmountedStyle, state, data, 1, true)}
  willLeave={() => getStyle(unmountedStyle, oldState, oldData, 1)}
  - styles={sceneContexts.map(({state, data, url, mount}) => ({
  + styles={sceneContexts.map(({state, data, url}) => ({
  key: url,
  - data: {scene: this.state.scenes[url], state, data, url, mount},
  + data: {scene: this.state.scenes[url], state, data, url, mount: url === nextCrumb.url},
  style: getStyle(mountedStyle, state, data, spring(0))
  }))}>
  {tweenStyles => (
  