Log Message:
textproc/R-selectr: import R-selectr-0.4.2

Translates a CSS3 selector into an equivalent XPath expression. This
allows us to use CSS selectors when working with the XML package as it
can only evaluate XPath expressions. Also provided are convenience
functions useful for using CSS selectors on XML nodes. This package is
a port of the Python package 'cssselect'
(<https://cssselect.readthedocs.io/>).