Hello!

I've opened the COPYING file and see the following (line 4): "Note that the only valid version of the GPL as far as this project is concerned is this particular version of the license (ie v2, not v2.2 or v3.x or whatever), unless explicitly otherwise stated".

In the same time line 319: "...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".

Please consider replacing the core license text with the GLPv2-only one.