Royal Society-Wolfson Bioinformatics Laboratory, School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK.|Royal Society-Wolfson Bioinformatics Laboratory, School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK.|Royal Society-Wolfson Bioinformatics Laboratory, School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK.