Center for Bioinformatics, Saarland University, Saarbrücken, Germany Max Planck Institute for Informatics, Saarbrücken, Germany Saarbrücken Graduate School of Computer Science, Saarland University, Saarbrücken, Germany.|Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, SE-17121 Solna, Sweden.|Center for Bioinformatics, Saarland University, Saarbrücken, Germany Max Planck Institute for Informatics, Saarbrücken, Germany.