The `regex` function has been removed (not `Deprecated`) as *regexr* is in beta
mode.  This move breaks backward compatibility and thus a bump in major release
to version 1.0.0.

* `regex` function replaced with the `subs` function.  This move is both
  semantic and pragmatic.  The term "regular expression chunk" has been
  replaced with "sub-expressions".  The `subs` function reflects the semantic
  change.  Additionally, Richie Cotton's *regex* package
  (https://github.com/richierocks/regex), which is complementary to *regexr*,
  contains a `regex` function.