Webbpsf-ext

Generate a MANIFEST.in to include `throughtputs` and `spectral_data` directories under `webbpsf_ext` installation location.

Update some package requirements, expand README, fix NIRCam grism bugs, add NIRCam wide-band blocking filter throughputs, nircam module case sensitivity for filter names, add RevAA prelaunch OPD by default.

First major release of `webbpsf_ext` package.