fixed generatino of offsets for hex lattice. Before offsets weer incorerctly generated for a 3D lattice which was less than 9 pizels wide in the z direction > this i is fairly minor problem but it is fixed no
fixed diffusion solver on hex lattice with non periodic bc conditions. For no flux BC total amount of chemical is preserved on hex lattice. BC are implemented in slightly different way now for hex lattice but this is a correct way as opposed to incorrect way in previous versions