Standardize Licensing

- License was intended to be GPLv3 per earlier commit of GPLv3 LICENSE FILE
- This is confirmed by the inclusion of libraries that are incompatible with GPLv2
- This is also confirmed by KLS and the agreement of KLS's predecessors
- Added GPLv3 license headers to the compilable source files
- Removed Folly licensing in strings.h since the string functions do not match the Folly functions and are standard functions - this must have been left over from previous implementations
- Removed individual contributor license headers since the project has been under the "developer" mantle for many years
- Removed comments on files that were previously automatically generated since they've been manually modified multiple times and there are no automatic scripts referencing them (removed in 2023)

zone/gm_commands/emptyinventory.cpp

@@ -1,3 +1,20 @@
+/*	EQEmu: EQEmulator
+
+	Copyright (C) 2001-2026 EQEmu Development Team
+
+	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/>.
+*/
 #include "zone/client.h"
 
 void command_emptyinventory(Client *c, const Seperator *sep)