rPref 1.0.0
===========

* Added BTG graph visualization function in the DOT language, 
  accessible via the function get_btg_dot.
  
* Removed dependency to dplyr::is.grouped_dt, as this will be 
  removed in dplyr > 0.4.3
  
* Updated unit tests to new testthat 1.0.0 expectation syntax