Computational Biology, Department of Physics, Linköping University, Linköping, Sweden. rolle@ifm.liu.se|Computational Biology, Department of Physics, Linköping University, Linköping, Sweden. rolle@ifm.liu.se|Computational Biology, Department of Physics, Linköping University, Linköping, Sweden. rolle@ifm.liu.se|Computational Biology, Department of Physics, Linköping University, Linköping, Sweden. rolle@ifm.liu.se