Add reformatter script for data from NIST

[RyanWollaeger]

The NIST tabular opacity data is nearly in the SuperNu 4.x parsed format, but not quite.
In particular, the following has to be done to use the NIST data in SuperNu:

• Select "all": the columns are then identical in content to the assumed columns of the parser.
• Choose the desired temperature and frequency range.
• Remove dividing lines between columns, and replace header (including column headers) with e.g.,

#start        4.175E+01   1.000E-02   1.253E-04   3.000E-06
# e,abs+st,tot+st,bb,bf,ff,scat

where the 2nd number is the temperature (the other numbers are ignored).

• Ensure the number of frequency points matches the assumed number in tbxsmod.f (currently 14900).
• For a particular density, concatenate the files over the range of temperatures, and ensure that the number of temperatures matches tbxsmod.f (currently 27).
• Ensure the number of tables per density matches the number of densities assumed in tbxsmod.f (currently 17).
• Name the files, e.g. “op_nd_1Em20gcc.table”, for “opacity, Nd, density=1e-20 g/cc”.