Fixes length calculations for new way of handling strings

lib.go

@@ -520,13 +520,13 @@ var stdLibrary = vars{
 		case []expression:
 			return number(len(i))
 		case string:
-			return number(len([]rune(i)))
+			return number(len([]rune(String(i, false))))
 		case exception:
-			return number(len([]rune(i)))
+			return number(len([]rune(String(string(i), false))))
 		case *IOHandle:
 			switch h := i.Obj.(type) {
 			case *strings.Builder:
-				return number(h.Len())
+				return number(len([]rune(String(h.String(), false))))
 			default:
 				return exception("'length' is not defined for a non-string-buf IOHandle")
 			}