Update to Pryaxis, 2018 part 2

If there's one thing I learned in this exercise, it's that letting
people add random python scripts to the repo like gpltext.py that
promise to be easier than find and replace is a bad idea.

TShockAPI/Extensions/ExceptionExt.cs

@@ -1,3 +1,21 @@
+/*
+TShock, a server mod for Terraria
+Copyright (C) 2011-2018 Pryaxis & TShock Contributors
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
 using System;
 namespace TShockAPI.Extensions
 {