Corrected copyright date in license file

diff --git a/LICENSE.txt b/LICENSE.txt
index 21096ad..8490d84 100644
--- a/LICENSE.txt
+++ b/LICENSE.txt
@@ -1,4 +1,4 @@
-Copyright (c) 2015-2018 KyrosKrane Sylvanblade
+Copyright (c) 2018 KyrosKrane Sylvanblade

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal