support for .NET framework 3.5

Still have bugs

Net35/HandyControl_Net35/Shell/Standard/MF.cs

@@ -0,0 +1,15 @@
+namespace Standard
+{
+    using System;
+
+    [Flags]
+    internal enum MF : uint
+    {
+        BYCOMMAND = 0,
+        DISABLED = 2,
+        DOES_NOT_EXIST = 0xffffffff,
+        ENABLED = 0,
+        GRAYED = 1
+    }
+}
+