feature/outer kore

**please review**

outer KORE sketch. will probably change as we start using it.
It seems I didn't make myself understood. I was not referring to the regex implementation -- I do not care about it. This is just about how the regex match is interpreted. 
What is the klabel for `syntax Foo ::= "foo" r"bar|buz"`? 
Furthermore, how does the KORE/KAST for "foobar" look like?