When the minor-mode clean-kill-ring-mode is enabled, any string that
satisfies one of the filter predicates in the clean-kill-ring-filters list
variable will not be allowed into the kill-ring.
By default clean-kill-ring-filters only contains the predicate
string-blank-p, which means that no blank lines will be allowed into the
kill-ring.
This package is available on MELPA.
MIT