add Lua bindings

stepmania/src/SongManager.h

@@ -9,6 +9,7 @@ class Style;
 class Course;
 class Steps;
 struct PlayerOptions;
+struct lua_State;
 
 #include "RageTypes.h"
 #include "GameConstantsAndTypes.h"
@@ -95,6 +96,9 @@ public:
 
 	void UpdateRankingCourses();	// courses shown on the ranking screen
 
+	// Lua
+	void PushSelf( lua_State *L );
+
 protected:
 	void LoadStepManiaSongDir( CString sDir, LoadingWindow *ld );
 	void LoadDWISongDir( CString sDir );