Max-Planck-Institute for Informatics, Department of Computational Biology and Applied Algorithmics, Stuhlsatzenhausweg 85, D-66123 Saarbrücken, Germany. osander@mpi-sb.mpg.de|Max-Planck-Institute for Informatics, Department of Computational Biology and Applied Algorithmics, Stuhlsatzenhausweg 85, D-66123 Saarbrücken, Germany. osander@mpi-sb.mpg.de|Max-Planck-Institute for Informatics, Department of Computational Biology and Applied Algorithmics, Stuhlsatzenhausweg 85, D-66123 Saarbrücken, Germany. osander@mpi-sb.mpg.de