Port of Re2j to C#

[Ken Domino]

Thought you'd like to know that I've started a port of Re2j to C#, https://github.com/kaby76/re2cs. It took a day to convert from Re2j and get it to compile, a testament to starting with clean code. I'm now working through the bugs I introduced (e.g., tolowercase/tolower differences even with various locales). Not surprising, C#'s Regex class fails with Cox's a?ⁿaⁿ against aⁿ example.