implemented '*_scr.med' archives decryption.

ArcFormats/DxLib/WidgetSCR.xaml.cs

@@ -0,0 +1,22 @@
+using System.Windows.Controls;
+using System.Linq;
+using GameRes.Formats.DxLib;
+using GameRes.Formats.Strings;
+
+namespace GameRes.Formats.GUI
+{
+    /// <summary>
+    /// Interaction logic for WidgetSCR.xaml
+    /// </summary>
+    public partial class WidgetSCR : StackPanel
+    {
+        public WidgetSCR()
+        {
+            InitializeComponent();
+            var keys = new string[] { arcStrings.ArcIgnoreEncryption };
+            ScriptScheme.ItemsSource = keys.Concat (MedOpener.KnownSchemes.Keys.OrderBy (x => x));
+            if (-1 == ScriptScheme.SelectedIndex)
+                ScriptScheme.SelectedIndex = 0;
+        }
+    }
+}