Use additional Itoh files when computing free-free emission

[wtbarnes]

In v9.0.1 and above of the database, there are two additional files used for computing the free-free continuum: itoh_integrated_gaunt.txt and itoh_integrated_gaunt_nonrel.txt, as noted in this mailing list post. However, it is not clear to me excatly how these new files are used in the new free-free calculation or whether one of them replaces the non-relativistic Sutherland Gaunt factors.

[jwreep]

Both files are used in ff_gaunt_itoh.pro, but I don't see what other routine calls this one.

ff_rad_loss.pro calls the Sutherland form, so perhaps this was meant to be included when relativistic forms are needed? (High temperatures?)

Perhaps ask Peter?