vctrs 0.2.4

• Factors and dates methods are now implemented in C for efficiency.

• new_data_frame() now correctly updates attributes and supports merging
  of the "names" and "row.names" arguments (#883).

• vec_match() gains an na_equal argument (#718).

• vec_chop()'s indices argument has been restricted to positive integer
  vectors. Character and logical subscripts haven't proven useful, and this
  aligns vec_chop() with vec_unchop(), for which only positive integer
  vectors make sense.

• New vec_unchop() for combining a list of vectors into a single vector. It
  is similar to vec_c(), but gives greater control over how the elements
  are placed in the output through the use of a secondary indices argument.

• Breaking change: When .id is supplied, vec_rbind() now creates
  the identifier column at the start of the data frame rather than at
  the end.

• numeric_version and package_version lists are now treated as
  vectors (#723).

• vec_slice() now properly handles symbols and S3 subscripts.

• vec_as_location() and vec_as_subscript() are now fully
  implemented in C for efficiency.

• num_as_location() gains a new argument, zero, for controlling whether
  to "remove", "ignore", or "error" on zero values (#852).