LICENSE: Add LICENSE file and files headers.

src/Model/Friction/Friction.py

@@ -1,3 +1,19 @@
+# Friction.py -- Pamhyr
+# Copyright (C) 2023  INRAE
+#
+# 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/>.
+
 # -*- coding: utf-8 -*-
 
 from tools import trace, timer