OTF2 THANKS file

OTF2 has originally been written by authors in AUTHORS file. Many
people further contributed to OTF2 by reporting problems, suggesting
various improvements or submitting actual code. Here is a list of
these people. Help me keep it complete and exempt of errors.

Martin Küttler                <martin.kuettler@os.inf.tu-dresden.de>
Ronald Geisler                <ronald.geisler@tu-dresden.de>
Alexander Grund               <alexander.grund@tu-dresden.de>
Samuel Thibault               <samuel.thibault@u-bordeaux.fr>
