posterior 1.4.0

Enhancements

• Added new rvar_factor() and rvar_ordered() subtypes of rvar() that work
  analogously to factor() and ordered() (#149). See the new section on
  rvar_factors in vignette("rvar").
• The draws_df(), draws_list(), and draws_rvars() formats now support
  discrete variables stored as factors / ordereds (or rvar_factors /
  rvar_ordereds). If converted to formats that do not support discrete
  variables with named levels (draws_matrix() and draws_array()),
  factor-like variables are converted to numerics.
• Made match() and %in% generic and added support for rvars to both
  functions.
• Added modal_category(), entropy(), and dissent() functions for
  summarizing discrete draws.
• Allow lists of draws objects to be passed as the first argument to
  bind_draws() (#253).
• Improving formatting of summarise_draws output via tibble::num.
• print.rvar() and format.rvar() now default to a smaller number of
  significant digits in more cases, including when printing in data frames.
  This is controlled by the new "posterior.digits" option (see
  help("posterior-package")).
• Implemented faster vec_proxy.rvar() and vec_restore.rvar(), improving
  performance of rvars in tibbles (and elsewhere vctrs is used).

Bug Fixes

• Ensure that as_draws_rvars() preserves dimensions of length-1 arrays (#265).
• Fix some minor compatibility issues with rvar, vctrs, dplyr, and
  ggplot2 (#267, #269).