hpa.spatial 0.2.1

• add get_correspondence_tbl() which calls strayr::read_correspondence_tbl()
  and if it fails to find one, it uses make_correspondence_tbl() to create
  one. Takes the same args as strayr::read_correspondence_tbl() but with the
  option to use a different mesh blocks edition/population data for
  make_correspondence_tbl().

• add make_correspondence_tbl() to create a correspondence table between two
  given geographies and a POINT geometry (sf) with population counts
  (Person as is standard in mesh blocks data).

• added a .data argument to map_data_with_correspondence() so that codes,
  values and groups can be passed by reference (like in dplyr::mutate()).

• always returna a tibble from map_data_with_correspondence() (just for
  consistency).

• add tests for (#3) which is a non-issue.