implemented XP3 archive creation.

ArcFormats/CreateXP3Widget.xaml.cs

@@ -0,0 +1,16 @@
+using System.Windows;
+using System.Windows.Controls;
+
+namespace GameRes.Formats.GUI
+{
+    /// <summary>
+    /// Interaction logic for CreateXP3Widget.xaml
+    /// </summary>
+    public partial class CreateXP3Widget : Grid
+    {
+        public CreateXP3Widget ()
+        {
+            InitializeComponent ();
+        }
+    }
+}