Enhancement: Add goodness of fit statistic values as additional evaluation tool

[lahdjirayhan]

trafficstars

I think of Anderson-Darling and/or Kolmogorov-Smirnov statistic.

Thoughts?

[cokelaer]

@lahdjirayhan thanks for using fitter. That would be nice. Unfortunatelly, I do not have much time those days to implement it. I'll be welcoming PR and contributions though ! If you are willing to provide a prototype or PR, I'll be happy to review/incorporate it. Best