FEATURES:
* (foo|bar) should be doable.
* Generally make some attempt to implement everything documented in
  perlre(1), or at least carp() that we aren't doing the right thing.
* Allow . to mean binary data in regular expressions (maybe with a flag
  to new()).
* Implement a way to over-ride the random function using a custom one.
    - This will allow platform-independent random number generators
    as well as Linux’s /dev/urandom / etc.