Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany. matthias@bioinf-uni-leipzig.de <matthias@bioinf-uni-leipzig.de>|Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany. matthias@bioinf-uni-leipzig.de <matthias@bioinf-uni-leipzig.de>