Naming convention for popgen stats and variables

[jeromekelleher]

#100 added functions Fst and Tajimas_D to the API. It's not clear that these are the right naming choices and we should make a conscious choice about what the variable/function naming conventions are. The most obvious choice is to make everything lowercase, (i.e., f_st/stats_f_st and tajimas_d/stats_tajimas_d), but arguably this is less readable that Fst/stats_Fst. We'll probably end up with a whole pile of stats like Garud's H stats (#231), Patterson's F[2-4] stats, the D, R and R2 LD stats

When we use letters to describe statistics, then the case does matter and it may be artificial to force them to be lowercase just for the sake of maintaining conventions ("A foolish consistency is the hobgoblin of little minds").

Ideally, we'd have descriptive names for things like we have for diversity and divergence, but I don't think that's practical. The established conventions in the field is for "[authors] [combination of letters]" to denote a statistic. The question is, what convention should we adopt for rendering "[authors] [combination of letters]" as a function name/variable name in the output dataset.

Related to #232 and #226

[tomwhite]

We should probably change Garud_h to Garud_H to be consistent with what we have done so far (Tajimas_D).

[jeromekelleher]

Good call.

[tomwhite]

Any objections to closing this one now?

[jeromekelleher]

Nope, done.