ps_diversity() now computes a smaller set of metrics
by default, in order to reduce runtimes.
ps_rand() includes a new choice of summary
statistic: in addition to the default “quantile” function, a new
“z-score” option is available.
ps_diversity() now includes several new divergence
and regularity measures, including terminal- and node-based versions of
mean pairwise distance (MPD) and variance in pairwise distance
(VPD).
ps_rand() now includes an explicit
"tip_shuffle" algorithm; previously this method could only
be implemented by supplying a custom randomization function.