Improve support for extending protocols to primitive arrays

It is possible to extend protocols to primitive arrays but specifying the class for the type is a little tricky:

However, things go bad if you try to do more than one of these:

The code in {parse-impls} is seeing the second {(Class/forName "[I")} as a function, not as a new type. One workaround for this is to only extend the protocol to one type at a time.

It would be even better (moving into enhancement area) if there was a syntax here to specify primitive array types - we already have the syntax of {bytes, ints, longs}, etc for type hints and those seem perfectly good to me.