Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, University of Leipzig, D-04107 Leipzig, Germany. htafer@bioinf.uni-leipzig.de|Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, University of Leipzig, D-04107 Leipzig, Germany. htafer@bioinf.uni-leipzig.de|Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, University of Leipzig, D-04107 Leipzig, Germany. htafer@bioinf.uni-leipzig.de|Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, University of Leipzig, D-04107 Leipzig, Germany. htafer@bioinf.uni-leipzig.de|Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, University of Leipzig, D-04107 Leipzig, Germany. htafer@bioinf.uni-leipzig.de