Copyright for blends source package in Focal

Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/

Files: *
Copyright: © 2003-2012 Andreas Tille 
License: GPL-2+

Files: devtools/blend-gen-control
Copyright: © 2018 Ole Streicher 
License: GPL-2+

Files: share/blends/*
Copyright: © 2003      Cosimo Alfarano 
           © 2003-2012 Andreas Tille 
License: GPL-2+

License: GPL-2+
 This package 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 2 of the License, or
 (at your option) any later version.
 .
 On Debian systems, the complete text of the GNU GPL version 2
 can be found in: `/usr/share/common-licenses/GPL-2'