Update README / Bump Copyright year (take 2)

Author: augustoproiete

README.md

@@ -72,7 +72,7 @@ The classes have been designed to resemble the original WPF classes to make it e
 
 ---
 
-Copyright (c) Sven Groot 2009
+Copyright (c) Sven Groot 2009-2018
 
 Copyright (c) Caio Proiete 2018-2020