dplyr 0.8.1

Breaking changes

group_modify() is the new name of the function previously known as group_map()

group_map() now only calls the function on each group and return a list.
group_by_drop_default(), previously known as dplyr:::group_drops() is exported (#4245).

Lists of formulas passed to colwise verbs are now automatically named.
group_by() does a shallow copy even in the no groups case (#4221).
Fixed mutate() on rowwise data frames with 0 rows (#4224).
Fixed handling of bare formulas in colwise verbs (#4183).
Fixed performance of n_distint() (#4202).
group_indices() now ignores empty groups by default for data.frame, which is
consistent with the default of group_by() (@yutannihilation, #4208).
Fixed integer overflow in hybrid ntile() (#4186).
colwise functions summarise_at() ... can rename vars in the case of multiple functions (#4180).
select_if() and rename_if() handle logical vector predicate (#4213).
hybrid min() and max() cast to integer when possible (#4258).
bind_rows() correctly handles the cases where there are multiple consecutive NULL (#4296).
Support for R 3.1.* has been dropped. The minimal R version supported is now 3.2.0.
https://www.tidyverse.org/articles/2019/04/r-version-support/
rename_at() handles empty selection (#4324).