speed up browsing media library

the way media library was searching for albums
was wrong and by the way totally inefficient.

src/settings.h

@@ -108,7 +108,6 @@ struct ncmpcpp_config
 	std::string song_status_format;
 	std::string song_window_title_format;
 	std::string song_library_format;
-	std::string media_lib_album_format;
 	std::string tag_editor_album_format;
 	std::string external_editor;