Added shortcut_run() and shortcut_get(), which make it easier to get and
run shortcuts by name (assigned name in the R code sense) when using
.shrtcts.R. This in turn makes it possible to use {shrtcts} to store
workflow shortcuts and to run these shortcuts in
Positron. (#26)
Use roxygen2::tag_words() instead of the deprecated roxygen2::tag_words_line()
when roxygen2 v8.0.0 or later is loaded.