Add multipopulation kind of analyses

[izabelcavassim]

This would be done to infer multi-population demographic models (such as figure 4 in paper 1 here

Not sure if they have it implemented in the first repository analyses, if so we can easily use it as a template.

[izabelcavassim]

Softwares to be used are:

• dadi
• fastsimcoal
• smc++ (if the conda env is fixed)
• momi2

[izabelcavassim]

This was previously organized here: https://github.com/popsim-consortium/analysis/tree/master/two_population_analysis

[izabelcavassim]

we basically just need to add momi2 to the workflow and merge it to the way @andrewkern has set up the whole snakemake workflow. Maybe we could work on that together @andrewkern? Thanks