Setting up source code for Avalonia port.

src.4.7/App.xaml.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Configuration;
+using System.Data;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace AdvancedCalculator
+{
+    /// <summary>
+    /// Interaction logic for App.xaml
+    /// </summary>
+    public partial class App : Application
+    {
+    }
+}