message: Replaced fragment instead of adding
  Found this out when trying shared element transition
diff: @@ -109,25 +109,17 @@ public class NavigationStackView extends ViewGroup {
  FragmentManager fragmentManager = ((FragmentActivity) mainActivity).getSupportFragmentManager();
  int enter = getAnimationResourceId(enterAnim, activityOpenEnterAnimationId);
  int exit = getAnimationResourceId(exitAnim, activityOpenExitAnimationId);
  - Fragment fragment, prevFragment = null;
  for(int i = 0; i < crumb - currentCrumb; i++) {
  int nextCrumb = currentCrumb + i + 1;
  String key = keys.getString(nextCrumb);
  SceneView scene = NavigationStackView.scenes.get(key);
  int popEnter = getAnimationResourceId(scene.enterAnim, activityCloseExitAnimationId);
  int popExit = getAnimationResourceId(scene.exitAnim, activityCloseEnterAnimationId);
  - fragment = new SceneFragment(scene);
  FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
  fragmentTransaction.setCustomAnimations(enter, exit, popEnter, popExit);
  - fragmentTransaction.add(((ViewGroup) this.getParent()).getId(), fragment, key);
  - if (nextCrumb > 0) {
  - if (prevFragment == null)
  - prevFragment = fragmentManager.findFragmentByTag(keys.getString(nextCrumb - 1));
  - fragmentTransaction.hide(prevFragment);
  - }
  + fragmentTransaction.replace(((ViewGroup) this.getParent()).getId(), new SceneFragment(scene), key);
  fragmentTransaction.addToBackStack(String.valueOf(nextCrumb));
  fragmentTransaction.commit();
  - prevFragment = fragment;
  }
  }
  if (crumb == currentCrumb && !oldKey.equals(keys.getString(crumb))) {
  