RegexFlags as newtype

[Fresheyeball]

No description provided.

[paf31]

The code looks nice, but I think this is only useful if we provide flags with individual options turned on, so that we can say, e.g.

flags = global <> sticky <> multiline

or

flags1 = flags && (not global)

[paf31]

Also, could you please add markdown comments to your new exported functions?

[paf31]

Also, I think the monoid dependency is a little unfortunate. Given the flags I mentioned above, I think Semigroup is probably enough, so can we remove it?

[Fresheyeball]

Oh sure.

[garyb]

Thanks for working on this, sorry it never went in! Nearly 2 years later we finally got there: #67