Center for Bioinformatics, Saarland University, Saarbrücken, Germany. amoll@bioinf.uni-saarland.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. amoll@bioinf.uni-saarland.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. amoll@bioinf.uni-saarland.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. amoll@bioinf.uni-saarland.de