uvred: interstellar extinction, Seaton Law

A UV reddening using Seaton's law (M.N.R.A.S. 187, 75p). Valid from 1000–3704Å. The transmission is set to unity shortward of the Lyman limit. This is incorrect physically but does allow the model to be used in combination with an X-ray photoelectric absorption model such as phabs.

 par1       E(B-V)