we need this function and it ISN'T IMPLEMENTED ANYWHERE. bring back DwiCompatibleStringToDifficulty as StringToDifficulty until a better solution is found.

src/Difficulty.cpp

@@ -35,6 +35,31 @@ const RString &CourseDifficultyToLocalizedString( CourseDifficulty x )
 	return g_CourseDifficultyName[x]->GetValue();
 }
 
+Difficulty StringToDifficulty( const RString& sDC )
+{
+	RString s2 = sDC;
+	s2.MakeLower();
+	if( s2 == "beginner" )			return Difficulty_Beginner;
+	else if( s2 == "easy" )		return Difficulty_Easy;
+	else if( s2 == "basic" )		return Difficulty_Easy;
+	else if( s2 == "light" )		return Difficulty_Easy;
+	else if( s2 == "medium" )		return Difficulty_Medium;
+	else if( s2 == "another" )		return Difficulty_Medium;
+	else if( s2 == "trick" )		return Difficulty_Medium;
+	else if( s2 == "standard" )	return Difficulty_Medium;
+	else if( s2 == "difficult")	return Difficulty_Medium;
+	else if( s2 == "hard" )		return Difficulty_Hard;
+	else if( s2 == "ssr" )			return Difficulty_Hard;
+	else if( s2 == "maniac" )		return Difficulty_Hard;
+	else if( s2 == "heavy" )		return Difficulty_Hard;
+	else if( s2 == "smaniac" )		return Difficulty_Challenge;
+	else if( s2 == "challenge" )	return Difficulty_Challenge;
+	else if( s2 == "expert" )		return Difficulty_Challenge;
+	else if( s2 == "oni" )			return Difficulty_Challenge;
+	else if( s2 == "edit" )		return Difficulty_Edit;
+	else							return Difficulty_Invalid;
+}
+
 LuaFunction( CourseDifficultyToLocalizedString, CourseDifficultyToLocalizedString(Enum::Check<Difficulty>(L, 1)) );
 
 CourseDifficulty GetNextShownCourseDifficulty( CourseDifficulty cd )