More aggressive caching. In general, this makes Stepmania avoid looking in the song directory at all if the song is in the cache, in order to load songs faster. All the RadarValue calculations were also rolled into one to reduce the time needed to build the cache.

src/Song.h

@@ -90,6 +90,7 @@ public:
 	bool LoadFromSongDir( RString sDir, bool load_autosave= false );
 	// This one takes the effort to reuse Steps pointers as best as it can
 	bool ReloadFromSongDir( RString sDir );
+	void LoadEditsFromSongDir(RString dir);
 
 	bool HasAutosaveFile();
 	bool LoadAutosaveFile();