units 0.8-6

• Add methods for cbind and rbind; fixes #311

• Performance improvements in data.frame methods; suggested in #361 @grcatlin

• Fix weighted.mean.units for unitless objects; #363

• Fix incorrect use of round() in %% and %/% methods; #365 @UchidaMizuki

• Fix ggplot2 deprecation warnings; #367

• Fix hist() error; #368

• Add support for lims() in ggplot2 scales; #370

• Fix simplification of inverse units; #378

• Replace call to Rf_error() with Rcpp::stop(); RcppCore/Rcpp#1247

• Fix UBs in the C++ glue code; #380

• Add support for brew path discovery in macOS; #384

• Several performance improvements; #387, #388, #393, #400 addressing #386, #389

• Improve keep_units() helper for more general usage scenarios;
  #394 @d-morrison addressing #392

• Add ud_convert() to convert units of a vector; #399 @dlebauer addressing #398

• Fix scale_units for upcoming version of ggplot2; #401