Make cosmological parameters configurable

[itaboada]

Currently Omega_M, Omega_Lambda and h_0 are hardcoded on Evolution.py

This is not high priority for neutrino astrophysics, to be honest. Many theorists simply do 0.3, 0.7 and 0.7

[renereimann]

Hej Ignacio,
I guess the cosmological parameters are already configurable.
See https://github.com/icecube/FIRESONG/blob/base/Evolution.py#L301
When you construct the LuminosityEvolution you can give it a cosmology dictionary that takes the settings for the cosmological parameters. The default is to use the parameters defined in https://github.com/icecube/FIRESONG/blob/base/Evolution.py#L6.

The cosmological parameters are propagated through and are an attribute of the classes.

The only missing thing is to add an argparse option for the executable scripts to modify it.