psfcalc: Rename get_psf to calculate_pinhole_psf; implement calculate_polychrome_pinhole_psf and get_polydisp_pts_wts.
psfcalc: Rename get_psf to calculate_pinhole_psf; implement calculate_polychrome_pinhole_psf and get_polydisp_pts_wts.

peri-source/peri