Most of the code was written by Neil Crighton, with some contributions
by Tom Theuns.

Acknowledgements
----------------

The voigt profile routine is inspired by a version written by Jochen
Liske in VPGUESS, which can be downloaded from:
http://www.eso.org/~jliske/vpguess/

The atom.dat file is taken from vpfit
(http://www.ast.cam.ac.uk/~rfc/vpfit.html), with several additions
from Verner et al.

The sed module was originally inspired by the astLib sed module by
Matt Hilton: http://astlib.sourceforge.net/.

The dust extinction law functions were inspired by those in Erik
Tollerud's Astropysics: http://packages.python.org/Astropysics/
