Bare numbers are used for multiplets in CSresolver and get_iso_statw.
Use of enums (ipDOUBLET, etc), instead, lends to more readable code.

We need to make sure that the fix in connection to the bug with the
order of the 'save species band' and 'init "honly.ini"' commands is
always exercised.

The function that computes the statistical weight for levels in He-like
species reports 4n^2 for all levels.  The 4 sums over both singlets and
triplets.  However, the ground has only a singlet state, no triplet.

This is the corollary of an earlier bug, which made the same mistake in
how the n-n' CS is broken up among the fine structure levels of a He-like
ground state.

The implementation omits the exponential term that appears in Eq. (8.30)
of Lebedev & Beigman, as it is folded in its conversion to a collision
strength.  Comment clarifies this point.

Fix bug in H2 line cooling

See merge request !25

Priyanka reported a floating point exception abort in one of her runs.
It came from a straight-up division in CoolH2_GA08.

Enclose all divisions in that function in safe_div calls.

21sep19

See merge request !24

The present coding effectively assumes that both singlets and triplets
are present in the ground of He-like ions, when in reality the ground
is a singlet.

The He-like ground now has a statistical weight of 1.  Fixed.

Hazy claims that the FeII bands are always processed, but this happens
only if a 'save' command has been given.  Move the command that enters
the FeII bands onto the stack of bands to be processed to the top of
SpeciesBandsCreate(), to make sure they are always added.

The 'save species bands' infrastructure uses two classes to store info
for each instance of the command.  The bands file and the species name
are stored as part of the t_save struct, while the data for summing the
band emission are stored in species_pseudo_cont.cpp.  Refactor the code
so that only one class exists that holds as data the parsed info as well
as an object of the class that sums up the emission.

Rename function to getSpeciesGeneric() to highlight that it deals to
user input, and move into said file -- a more natural home than
species_pseudo_cont.cpp and species.h.

Also, modify its interface to be similar to matchGeneric().

Gary sent a bug report that triggered an error with setting up the
"FeII_bands.ini" file in a sim that contained a 'save' command, and
'init "honly.ini"', in that order.

The problem occurred because ParseSave() specified "FeII_bands.ini" for
loading.  Iron was disabled later, so the "Fe+" species was not entered
in the list of species known to the code.  This triggered an abort when
the code tried to set up the FeII bands.

Make sure that the species is active before attempting to set up bands.
This requires that the bands are initialized after the atomic data have
been read in -- the relevant calls have been moved to cloudy().

The initialization of pseudo continua has also been moved to cloudy(),
for symmetry.

document increase in limit to Fe 17 levels

See merge request !23

We updated the LAMDA model of CN to their hyperfine
split version.  Many CN lines that were multiplets
are now individual lines.  We now find one of the
lines and obtain its intensity rather than the full
intensity of the multiplet.  We would need to create
a number of create line blends to get the multiplet
intensity.  Those are inconvenient since then all lines
have the same label “Blnd” and so are hard to identify
in the output.

This change puts us back to the previous state with the
non-resolved model and the full multiplet intensity being
obtained.  The LAMDA masterlist file has both
versions present with a comment on how to go to
the fully hyperfine split model.

We need to look into the literature to see what is
actually observed.  Do most telescopes measure
the multiplet individual members?  What do most
observational studies do?

we should have given the change date and the reason for the change.

Occurred in the defintion of save_img_matrix mathods in save.cpp, where
some methods used the same names in their API as some class variables.
Fixed.

Parameter gLo to GetHlikeCollisionStrength() is no longer used.  Remove
it to silence compiler warning.