[GameState] add GetExpandedSectionName() Lua binding.

Docs/Changelog_sm5.txt

@@ -16,6 +16,7 @@ StepMania 5.0 Preview 3 | 20110???
 * [GameState, SongUtil] Fix Issue 263 by not charging 2x stages for doubles when
   not using joint premium. [AJ]
 * [BeginnerHelper] Made BeginnerHelper run the OnCommand. [AJ]
+* [GameState] add GetExpandedSectionName() Lua binding. [AJ]
 
 2011/08/06
 ----------

src/GameState.cpp

@@ -2423,6 +2423,7 @@ public:
 			p->m_pCurCharacters[Enum::Check<PlayerNumber>(L, 1)] = c;
 		return 0;
 	}
+	static int GetExpandedSectionName( T* p, lua_State *L )				{ lua_pushstring(L, p->sExpandedSectionName); return 1; }
 	static int Dopefish( T* p, lua_State *L )
 	{
 		lua_pushboolean(L, p->m_bDopefish);
@@ -2526,6 +2527,7 @@ public:
 		ADD_METHOD( GetCurMusicSeconds );
 		ADD_METHOD( GetCharacter );
 		ADD_METHOD( SetCharacter );
+		ADD_METHOD( GetExpandedSectionName );
 		ADD_METHOD( Dopefish );
 	}
 };