Lots of code refactoring to use XAML behaviors instead of code-behind

New Save button in the AppBar
EntryPage now uses the same AppBar as GroupPage (but not shared...)
Some new Symbol mappings

ModernKeePass/Pages/MainPage.xaml.cs

@@ -0,0 +1,34 @@
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Navigation;
+using ModernKeePass.Pages;
+using ModernKeePass.ViewModels;
+
+// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238
+
+namespace ModernKeePass
+{
+    /// <summary>
+    /// An empty page that can be used on its own or navigated to within a Frame.
+    /// </summary>
+    public sealed partial class MainPage
+    {
+        public MainVm Model => (MainVm)DataContext;
+
+        public MainPage()
+        {
+            InitializeComponent();
+        }
+
+        protected override void OnNavigatedTo(NavigationEventArgs e)
+        {
+            base.OnNavigatedTo(e);
+            DataContext = new MainVm(Frame, MenuFrame);
+            if (Model.SelectedItem == null) MenuFrame.Navigate(typeof(WelcomePage));
+        }
+
+        private void ListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            Model.SelectedItem?.Destination.Navigate(Model.SelectedItem.PageType, Model.SelectedItem.Parameter);
+        }
+    }
+}