Fix parameter annotations throwing syntax error in optional / keyword parameters; Fix stream imports
Looks like the problem was only seen when compiling with make, but not when compiling with ant (which is what I used). Sorry for not verifying all compilation methods last time.
The issue was that it tried parsing annotations not only from required parameters, but also from keyword or optional.
I also removed stream-type import in stream-derived, since stream type was already being reexported from stream-primitive (as a result, I was getting duplicate declaration error)