/*
 * Get the duration of a song, in milliseconds
 *
 * This method raises an Xmms::Error exception if XMMS is not running,
 * or an ArgumentError exception if the number of arguments isn't 0 or
 * 1.
 *
 * Examples:
 *   # get the duration of the current song
 *   time = remote.playlist_time
 *
 *   # get the duration of song 23 in the playlist
 *   time = remote.playlist_time 23
 *
 */
static VALUE xr_pl_time(int argc, VALUE *argv, VALUE self) {