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

demo/Sandbox/Views/MainWindow.axaml

@@ -0,0 +1,45 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="using:Sandbox.ViewModels"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:u="https://irihi.tech/ursa"
+        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+        x:Class="Sandbox.Views.MainWindow"
+        x:DataType="vm:MainWindowViewModel"
+        Icon="/Assets/avalonia-logo.ico"
+        Title="Sandbox">
+
+    <Design.DataContext>
+        <!-- This only sets the DataContext for the previewer in an IDE,
+             to set the actual DataContext for runtime, set the DataContext property in code (look at App.axaml.cs) -->
+        <vm:MainWindowViewModel/>
+    </Design.DataContext>
+
+    <Grid>
+        <DataGrid ItemsSource="{Binding Items}" IsReadOnly="False" HorizontalAlignment="Left">
+            <DataGrid.Columns>
+                <DataGridTextColumn Header="Name" Binding="{Binding Name}"/>
+                
+                <DataGridTemplateColumn Width="2*" Header="Address" MaxWidth="300" MinWidth="300">
+                    <DataGridTemplateColumn.CellTemplate>
+                        <DataTemplate>
+                            <TextBlock
+                                HorizontalAlignment="Center"
+                                VerticalAlignment="Center"
+                                Text="{Binding Address}" />
+                        </DataTemplate>
+                    </DataGridTemplateColumn.CellTemplate>
+                    <DataGridTemplateColumn.CellEditingTemplate>
+                        <DataTemplate>
+                            <u:IPv4Box
+                                HorizontalAlignment="Stretch"
+                                IPAddress="{Binding Address}" />
+                        </DataTemplate>
+                    </DataGridTemplateColumn.CellEditingTemplate>
+                </DataGridTemplateColumn>
+            </DataGrid.Columns>
+        </DataGrid>
+    </Grid>
+
+</Window>