possible duplication: various metric/likelihood definitions

[LeanderFischer]

Is it intended that there are multiple (possible duplicate) definitions of the same likelihoods stats.py, likelihood_functions.py, and llh_defs? Maybe these could be streamlined/combined.

[JKrishnamoorthi]

1. The second and third hyperlinks are not working (maybe moved/removed).
2. I don't find any duplicate between stats.py and likelihood_functions.py
3. Functions in stats.py (barlow_llh(), poisson_gamma()) depend on the functions in likelihood_functions.py (barlowLLH(), mcllh_mean())