fix: fix IPV4Box key handling in DataGrid. Add a SampleBox project for extra testing. Upgrade to released version.

demo/Sandbox/Program.cs

@@ -0,0 +1,20 @@
+using Avalonia;
+using System;
+
+namespace Sandbox;
+
+sealed class Program
+{
+    // Initialization code. Don't use any Avalonia, third-party APIs or any
+    // SynchronizationContext-reliant code before AppMain is called: things aren't initialized
+    // yet and stuff might break.
+    [STAThread]
+    public static void Main(string[] args) => BuildAvaloniaApp()
+        .StartWithClassicDesktopLifetime(args);
+
+    // Avalonia configuration, don't remove; also used by visual designer.
+    public static AppBuilder BuildAvaloniaApp()
+        => AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+            .LogToTrace();
+}