Release 1.2.1 is a quick patch follow up to 1.2.0

Tplyr 1.2.1

Resolve #178 to add metadata handling for missing subjects, and add the add_anti_join() function

Tplyr 1.2.0

Resolve #62 Add data vignette data into the package (thanks for the suggestion @thebioengineer)
Resolve #74 Add an example of piping in set_pop_data
Resolve #83 Add the add_missing_subjects() function
Resolve #84 Add set_limit_data_by() function
Resolve #111, #148 Allow ellipsis argument unpacking outside of add_layer()
Resolve #129 Add collapse_row_labels() function
Resolve #134 Clarify how population data works to trigger denominators
Resolve #75, #146, #166 Fix nested count layer handling where one inner layer value exists in multiple outer layer groups
Resolve #21, #152 Fix handling of Inf, -Inf in desc layer for min and max
Resolve #154 Fix namespace scoping for execution of Tplyr tables within non-global environments
Resolve #155 Dead code clean-up
Resolve #170 Add replace_leading_whitespace() post-processing function
Resolve #173 Fix nested count layer sort variable behavior when using by variables