Add more scale types

Elwig/App.xaml.cs

@@ -50,6 +50,8 @@ namespace Elwig {
                     int? limit = s[6] == null ? null : int.Parse(s[6]);
                     if (type == "systec") {
                         list.AddLast(new SystecScale(scaleNr, model, cnx, empty, filling, limit));
+                    } else {
+                        throw new ArgumentException($"Invalid scale type: \"{type}\"");
                     }
                 } catch (Exception e) {
                     MessageBox.Show($"Unable to create scale {s[0]}:\n\n{e.Message}", "Scale Error", MessageBoxButton.OK, MessageBoxImage.Error);