add some demos & styles

1. add window demo
2. add scrollviewer demo
3. add radiobutton style
4. fixed some bugs
5. add research project

HandyControlDemo/UserControl/Controls/ScrollViewerDemoCtl.xaml.cs

@@ -0,0 +1,11 @@
+// ReSharper disable once CheckNamespace
+namespace HandyControlDemo.UserControl
+{
+    public partial class ScrollViewerDemoCtl
+    {
+        public ScrollViewerDemoCtl()
+        {
+            InitializeComponent();
+        }
+    }
+}