Algorithmic Bioinformatics, Bonn-Aachen International Center for IT, Bonn D-53113, Germany.|DIMNP UMR CNRS 5235, University of Montpellier, Montpellier, France.|Institut für Informatik II, University of Bonn, Bonn 53113, Germany.|Algorithmic Bioinformatics, Bonn-Aachen International Center for IT, Bonn D-53113, Germany.