Parameters shouldn't be hard-coded in the module

[giordano]

We currently have the file src/params.jl with parameters hard-coded into the module.

I did this in the quick proof-of-concept following the example of the original code, but in the long term this is not a good practice. Maybe read from a file?

[tkoskela]

This is needed to test more of the code's functions since we can't override the parameters for smaller test runs right now.