School of Mathematical Sciences, University of Adelaide, Adelaide, Australia. sean.robinson@alumni.adelaide.edu.au.|School of Mathematical Sciences, University of Adelaide, Adelaide, Australia. gary.glonek@adelaide.edu.au.|School of Mathematical Sciences, University of Adelaide, Adelaide, Australia. inge.koch@adelaide.edu.au.|CSIRO Agriculture, Adelaide, Australia. mark.r.thomas@csiro.au.|CSIRO Agriculture, Adelaide, Australia. christopher.davies@csiro.au.