support for .NET framework 3.5

Still have bugs

Net35/HandyControlDemo_Net35/UserControl/Controls/ImageBrowserDemoCtl.xaml.cs

@@ -0,0 +1,14 @@
+
+namespace HandyControlDemo.UserControl
+{
+    /// <summary>
+    /// ImageBrowserDemoCtl.xaml 的交互逻辑
+    /// </summary>
+    public partial class ImageBrowserDemoCtl
+    {
+        public ImageBrowserDemoCtl()
+        {
+            InitializeComponent();
+        }
+    }
+}