Fix `regexRegex` and `regexParser`
Fix `regexRegex` and `regexParser`

- the regex does not consume comments now
- no repitition of flags is allowed
- only five flags are possible now [`gmuiy`], in any order
- change parameters of lambda function in `regexParser` to
  accomodate the new capturing group added to the regex.

cleanlang/clean,cleanlang/clean,cleanlang/clean