Use NIST ionization potentials, not phfit.dat
Previously, Cloudy used various sources for ionization potentials:
the ionization_potentials.dat
file that uses NIST values;
the (valence) shell ionization energies in phfit.dat
(by Dima Verner);
and for the H and He iso-sequences, values embedded in the data files
(.nrg.dat
, in data/stout/
).
In one instance this has led to a bug with the set continuum resolution
command.
This branch eliminates use of other sources of IP data in favor of the NIST values.