Add a measure similar to typing resolution score

[gbiagini]

"Might be interesting to also show a TRS-like metric for distribution of AA polymorphisms per position conditional on just knowing allele freqs for the populations." - Dr. Gragert

[gbiagini]

Paunić V, Gragert L, Schneider J, et al (2016) Charting improvements in US registry HLA typing ambiguity using a typing resolution score. Hum Immunol 77:542–549. https://doi.org/10.1016/j.humimm.2016.05.002