enh: Add index-based Point coordinate accessors [Numerics]
enh: Add index-based Point coordinate accessors [Numerics]

stefanpsz/MIRTK,BioMedIA/MIRTK,schuhschuh/MIRTK,BioMedIA/MIRTK,schuhschuh/MIRTK,schuhschuh/MIRTK,BioMedIA/MIRTK,stefanpsz/MIRTK,stefanpsz/MIRTK,stefanpsz/MIRTK,BioMedIA/MIRTK,schuhschuh/MIRTK