/*
 * Return the current playlist.  If a block is given, pass each playlist
 * element to the block.
 *
 * This method raises an Xmms::Error exception if XMMS is not running.
 *
 * Note: Returning the full array can be very slow for large playlists;
 * use the block form instead.
 *
 * Example:
 *   # print out info for each element in the playlist
 *   ary = remote.playlist
 *   ary.each do |ary|
 *     title, file, time = ary
 *     puts "'#{title}' (#{time}ms), #{file}"
 *   end
 *
 *   # print out info for each element in the playlist (using block 
 *   # syntax; much faster)
 *   remote.playlist { |e| puts "'#{e[0]}' (#{e[2]}), #{e[1]}" }
 *
 */
static VALUE xr_pl(VALUE self) {