lyman: Voigt absorption profiles for H I or He II Lyman series

This model calculates the Voigt absorption profiles for the H I and He II Lyman series.

par1 n: H I or He II column density ($10^{22}$ atoms/cm$^2$)
par2 b: b value (km/s)
par3 z: Redshift
par4 ZA: Atomic number of species being calculated.