/*
 * Is the shuffle flag set?
 *
 * Examples:
 *   puts 'shuffling' if remote.is_shuffling?
 *   puts 'shuffling' if remote.shuffling?
 *   puts 'shuffling' if remote.is_shuffle?
 *   puts 'shuffling' if remote.shuffle?
 *
 */
static VALUE xr_shuffle(VALUE self) {