1. Institute for Theoretical Physics, University of Münster, Wilhelm-Klemm-Str. 9, D-48149 Münster, Germany
2. Departament de Física, Universitat de les Illes Balears, and Institute of Applied Computing and Community Code (IAC-3), C/ Valldemossa km 7.5, 07122 Mallorca, Spain
3. Center for Nonlinear Science (CeNoS), University of Münster, Corrensstrasse 2, D-48149 Münster, Germany