pysynphot to synphot

[JarronL]

Move from pysynphot to synphot package (https://synphot.readthedocs.io/en/latest/). See also https://synphot.readthedocs.io/en/latest/synphot/from_pysyn_iraf.html for porting.

1. utils.py
   • import pysynphot as S
   • S.refs.set_default_waveset (is this needed anymore?)
   • S.refs.setref(area = 25.78e4) (area is now specified during effstim calls)
2. bandpasses.py
   • Lots to do
3. spectra.py
   • Lots to do
4. image_manip.py
   • model_to_hdulist function
5. psfs.py
   • create_obslist function
   • gen_image_from_coeff function
6. webbpsf_ext_cor.py
   • bandpass attributes
   • _calc_psf_from_coeff function