Dept Bioinformatics, Wellcome Trust Centre, Oxford, UK. fredrikp@well.ox.ac.uk|Dept Bioinformatics, Wellcome Trust Centre, Oxford, UK. fredrikp@well.ox.ac.uk|Dept Bioinformatics, Wellcome Trust Centre, Oxford, UK. fredrikp@well.ox.ac.uk|Dept Bioinformatics, Wellcome Trust Centre, Oxford, UK. fredrikp@well.ox.ac.uk