Bioinformatics Research Centre, Department of Computer Science, Aarhus University, 8000 Aarhus C, Denmark, Biophysics Graduate Group, Computer Science Division, Department of Statistics and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA Bioinformatics Research Centre, Department of Computer Science, Aarhus University, 8000 Aarhus C, Denmark, Biophysics Graduate Group, Computer Science Division, Department of Statistics and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA Bioinformatics Research Centre, Department of Computer Science, Aarhus University, 8000 Aarhus C, Denmark, Biophysics Graduate Group, Computer Science Division, Department of Statistics and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.