mrgrid: ensure no oversampling when using nearest-neighbour interpolation
mrgrid: ensure no oversampling when using nearest-neighbour interpolation

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3