Resolve "license headers"

Closes #8 (closed)

scripts/license_header_2021.txt

+// Copyright (C) 2020,2021 Institut de Robòtica i Informàtica Industrial, CSIC-UPC.
+// Authors: Angel Santamaria-Navarro (asantamaria@iri.upc.edu)
+// All rights reserved.
+//
+// This file is part of vision_utils
+// vision_utils is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.