Fancy-Regex 0.18.0 Release

Exactly one year on from Oniguruma's archival on GitHub and fancy-regex is in a pretty good position to act as a compatible, memory-safe alternative.

Since the previous release, fancy-regex now has support for subroutine calls - although relative recursion level backreferences are still currently unsupported.

There also a PR with an experimental optimization, which may get released soon.