[ScreenSelectMusic] add a code for closing the current folder from any location (a la DDR X2)

[metric will be added with the next batch of theme commits]

src/CodeDetector.cpp

@@ -51,6 +51,7 @@ const char *CodeNames[] = {
 	"SaveScreenshot2",
 	"CancelAllPlayerOptions",
 	"BackInEventMode",
+	"CloseCurrentFolder",
 };
 XToString( Code );
 
@@ -76,6 +77,11 @@ void CodeDetector::RefreshCacheItems( RString sClass )
 	}
 }
 
+bool CodeDetector::EnteredCloseFolder( GameController controller )
+{
+	return EnteredCode(controller,CODE_CLOSE_CURRENT_FOLDER);
+}
+
 bool CodeDetector::EnteredNextGroup( GameController controller )
 {
 	return EnteredCode(controller,CODE_NEXT_GROUP);