added licence information

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>

COPYING

+LICENCE
\ No newline at end of file

LICENCE

+Copyright © 2008–2022 Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
+
+
+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 <https://www.gnu.org/licenses/>.