Add license to legacy utilities

Generated using script:
for file in \$(find ./legacy -type f | \grep -E "\.cpp|\.h")
do
  mv $file temp.xxx
  cp gplheader $file
  cat temp.xxx >> $file
done

legacy/editor/ScriptLevelInterface.cpp

@@ -1,3 +1,21 @@
+/*
+* Descent 3 
+* Copyright (C) 2024 Parallax Software
+*
+* 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/>.
+*/
+
 /*
 * $Logfile: /DescentIII/Main/editor/ScriptLevelInterface.cpp $
 * $Revision: 1.1.1.1 $