RegexMatchableObject improvement

[Necr0x0Der]

There is RegexMatchableObject with regex: token, which could be used for doing fun stuff like:

(= (f regex:"^[1-9]") Number)
(= (f $x) Empty)
!(f "12") ; Number
!(f "aaa") ; Empty

However, there are no examples of using regex: and just a few tests, and its implementation is somewhat weird, e.g., it uses flags=re.IGNORECASE for unknown reason.
It might be desirable to improve RegexMatchableObject and make it more usable. Maybe, one could make it work on Symbol atoms as well.