Adds new ice models for upward and downward systematics.

[Machtay]

The new ice models are 41 and 42. They add the systematics from here to the ice model 40 parameters: https://aradocs.wipac.wisc.edu/0035/003525/002/5SA_Ice_Model_Uncertainties.pdf

[marcomuzio]

Thanks @Machtay this looks good. Can you just add these to the high-level docs in Settings.h?

AraSim/Settings.h

Line 287 in f6387a5

int RAY_TRACE_ICE_MODEL_PARAMS; // which parameter set is used for the exponential ice model (defined in RayTrace_IceModel.cc)

[clark2668]

Agreed about adding to docs, otherwise good.

[Machtay]

Added to the docs

[marcomuzio]

Thanks!