Computational Biology & Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, Building E1.4, Saarbruecken, D-66123, Germany. snikumbh@mpi-inf.mpg.de.|Computational Biology & Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, Building E1.4, Saarbruecken, D-66123, Germany.