forcats 0.3.0

API changes

• fct_c() now requires explicit splicing with !!! if you have a
  list of factors that you want to combine. This is consistent with an emerging
  standards for handling ... throughout the tidyverse.

• fct_reorder() and fct_reorder2() have renamed fun to .fun to
  avoid spurious matching of named arguments.

New features

• All functions that take ... use "tidy" dots: this means that you use can
  !!! to splice in a list of values, and trailing empty arguments are
  automatically removed. Additionally, all other arguments gain a . prefix
  in order to avoid unhelpful matching of named arguments (#110).

• fct_lump() gains w argument (#70, @wilkox) to weight value
  frequencies before lumping them together (#68).

Improvements to NA handling

• as_factor() and fct_inorder() accept NA levels (#98).

• fct_explicit_na() also replaces NAs encoded in levels.

• fct_lump() correctly acccounts for NA values in input (#41)

• lvls_revalue() preserves NA levels.

Minor improvements and bug fixes

• Test coverage increased from 80% to 99%.

• fct_drop() now preserves attributes (#83).

• fct_expand() and lvls_expand() now also take character vectors (#99).

• fct_relabel() now accepts objects coercible to functions
  by rlang::as_function (#91, @alistaire47)