NTS unpack functions

[aaronbojarski]

I see. So the other question would then be, whether it wouldn't actually be cleaner to get rid of pos as a parameter of method unpack and to call it with the minimal slice necessary for its job like, e.g., eh.unpack(b[pos:pos + 4]) and x.unpack(b[pos + 4:pos + int(eh.Length)]). But maybe that's also something for a future iteration of this package.

Originally posted by @marcfrei in #12 (comment)