v1.5.21 updated plot_richness for more flexibility. Needs testing.
v1.5.21 revise plot_richness/estimate_richness
v1.5.21 plot/estimtate_richness update. A bug remains.

A bug if choose a set of methods that don't have a s.e. estimate. Just
need a simple check/protect around the s.e.-specific section(s).
v1.5.21 - `plot_richness` / `estimate_richness` updates

phyloseq 1.5.21 - `plot_richness` / `estimate_richness` updates
===========
-- Additional alpha-diversity measures added to both functions.
-- New argument, `measures`, added to both functions, allows user to
   specify which measures to calculate/display.
-- Also added unit tests for both functions, absent in prior versions
Merge pull request #239 from joey711/update-diversity-methods

v1.5.21 - `plot_richness` / `estimate_richness` updates