Earlham Institute, Norwich Research Park, Norwich NR4 7UZ, UK.|Earlham Institute, Norwich Research Park, Norwich NR4 7UZ, UK.|Merseburg University of Applied Sciences, 06217 Merseburg, Germany.|School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK.|Department of Computer Science, University of Tübingen, Sand 14, 72076 Tübingen, Germany.|School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK.