Geometric mean as a measure

[dkuzi]

Is it possible to include the geometric mean as a measure for benchmark runs? Similar to how median and mean are simple reexports from Statistics.jl it should be possible to reexport the geometric mean geomean from StatsBase.jl. Is this a feature worth considering for you?

Alternatively, you can omit the additional dependency StatsBase and define the geometric mean in-package since it is literally one line using the form geomean(a) = exp(mean(log, a)) as it is implemented in StatsBase, see here.

[willow-ahrens]

I think this is great! I would be happy to review a PR which adds this functionality as an Extension package when StatsBase is loaded, for geomean and harmonic mean