Feature request: allow extracting regexes and results into JSON

[stsewd]

Hi, thanks for this library, it's very useful. Having the output in the stdout is great, but for bigger projects it may not be easy to parse for further analysis or some automation.

This is a request for an option like --extract [file.json] for regexploit-py (to start, it could be expanded to other scripts). Let me know if you are open to such feature, I can send a PR for it.