new screen: music visualizer

src/settings.h

@@ -71,6 +71,7 @@ struct ncmpcpp_keys
 	int PlaylistEditor[2];
 	int TagEditor[2];
 	int Outputs[2];
+	int Visualizer[2];
 	int Clock[2];
 	int Stop[2];
 	int Pause[2];
@@ -126,6 +127,7 @@ struct ncmpcpp_config
 {
 	std::string mpd_host;
 	std::string mpd_music_dir;
+	std::string visualizer_fifo_path;
 	std::string empty_tag;
 	std::string song_list_columns_format;
 	std::string song_list_format;