private async void ListView_Loaded(object sender, RoutedEventArgs e)
{
ListView elencoLinee = (ListView)sender;
elencoLinee.ItemsSource = await DBSource.getTrattePreLoad();
elencoLinee.ItemsSource = await DBSource.Tratte;
ObservableCollection <Linea> trat = await DBSource.Tratte;
System.Diagnostics.Debug.WriteLine(trat.Count);
}