index_to_coord(): Python 3 fix: was relying on floored division before with /, fixed by using //.
index_to_coord(): Python 3 fix: was relying on floored division before with /, fixed by using //.

Applemann/hypatia,brechin/hypatia,brechin/hypatia,Applemann/hypatia,lillian-lemmer/hypatia,hypatia-software-org/hypatia-engine,lillian-lemmer/hypatia,hypatia-software-org/hypatia-engine