message: Removed scene transparency
  It was so that fluently navigated blank scenes didn't show during animation, but think changing to replace has meant they don't show up
diff: @@ -104,13 +104,12 @@ class Scene extends React.Component<SceneProps, SceneState> {
  var {crumb, title, sceneKey, popped, navigationEvent: {stateNavigator}} = this.props;
  var {crumbs} = stateNavigator.stateContext;
  var {state, data} = navigationEvent ? navigationEvent.stateNavigator.stateContext : crumbs[crumb];
  - var backgroundColor = navigationEvent ? '#fff' : 'rgba(255,255,255, 0)';
  return (
  <NVScene
  sceneKey={sceneKey}
  {...this.getAnimation()}
  title={title(state, data)}
  - style={[styles.scene, {backgroundColor}]}
  + style={styles.scene}
  onWillAppear={this.onWillAppear}
  onPopped={() => popped(sceneKey)}>
  <BackButton onPress={this.handleBack} />
  @@ -126,6 +125,7 @@ var NVScene = requireNativeComponent<any>('NVScene', null);
  const styles = StyleSheet.create({
  scene: {
  + color: '#fff',
  position: 'absolute',
  top: 0, right: 0,
  bottom: 0, left: 0,
  