It's a tuple boolean/Match Value - "is it matched?"/"actual match"

First draft of Match value type with some tests. MatchVector does not yet properly implement first/last token, hence a test fails, and AnnotationMatch is pretty much a stub.

Previously effectively agreement was checked on all categories,
even if a lexeme's tag didn't have some of the selected categories.
That led to treating such lexeme as not agreeing with one that had
more matching categories, even if it was agreeing on all categories
that were present.