Fix sound modifier parameter in SoundAt script function.

The modifier was created but not applied.

src/gamescript/C4GameScript.cpp

@@ -517,7 +517,7 @@ static bool FnSoundAt(C4PropList * _this, C4String *szSound, long iX, long iY, N
 		iX += pObj->GetX();
 		iY += pObj->GetY();
 	}
-	StartSoundEffectAt(FnStringPar(szSound), iX, iY, iLevel, iCustomFalloffDistance, iPitch);
+	StartSoundEffectAt(FnStringPar(szSound), iX, iY, iLevel, iCustomFalloffDistance, iPitch, modifier);
 	// always return true (network safety!)
 	return true;
 }