Method and instrument comparison

compare_methods(methodA, methodB; method=:ba)
compare_instruments(a, b; method=:passing_bablok)
compare_lots(data, :lot)
compare_sites(data; site=:site)

Method	Reference
`:ba`	Bland–Altman (Bland and Altman, 1986)
`:passing_bablok`	Passing & Bablok (Passing and Bablok, 1983); slope and intercept 95% CIs in `details`
`:deming`	Errors-in-variables regression
`:robust`	Theil–Sen (Theil, 1950) (Sen, 1968)

Lot comparison reports location (Kruskal–Wallis), variance (Brown–Forsythe (Brown and Forsythe, 1974)), and optional two-sample KS.