clarified consent to use under MIT

Terminal.Gui/Views/TreeView.cs

@@ -1,4 +1,4 @@
-// This code is based on http://objectlistview.sourceforge.net (GPLv3 tree/list controls by [email protected])
+// This code is based on http://objectlistview.sourceforge.net (GPLv3 tree/list controls by [email protected]).  Phillip has explicitly granted permission for his design and code to be used in this library under the MIT license.
 
 using System;
 using System.Collections.Generic;