provide a way to sync between visualization and sound

workaround for http://musicpd.org/mantis/view.php?id=2503

src/settings.h

@@ -131,6 +131,7 @@ struct ncmpcpp_config
 	std::string mpd_host;
 	std::string mpd_music_dir;
 	std::string visualizer_fifo_path;
+	std::string visualizer_output_name;
 	std::string empty_tag;
 	std::string song_list_columns_format;
 	std::string song_list_format;