v0.8.0

• Added option rules.captureGroup (equivalent to Oniguruma compile-time option ONIG_OPTION_CAPTURE_GROUP) to toDetails, toRegExp, and toOnigurumaAst. Allows unnamed captures and numbered backreferences/subroutines when using named capture (with complex resulting rules in edge cases).
• When using option allowUnhandledGAnchors, don't add flag y for unsupported \G (provides better tradeoffs).
• When not using option avoidSubclass, use emulation groups (which prevent captured values from appearing on the result array) for copies of capturing groups created by recursion.
• Fix: Prevent ^ from matching after a string-terminating line feed. (#9)