Method Call Assist: fix for functional notation

[jamshark70]

This is fine:

a.max(b)

After typing the opening paren and choosing the class, the argument pop up shows operand, adverb as expected.

This is not fine:

max(a, b)

After typing the opening paren, the argument pop up shows operand, adverb but what is really correct in this case would be receiver, operand, adverb. It looks to the user, then, that "b" is the adverb, but it's really the operand.

Alternately, in place of "receiver" -- the user has chosen the desired class, so it could prepend "a" or "an" in front of the class name, e.g., aSimpleNumber, operand, adverb.

[jleben]

Fixed.
For now, we display "receiver"; we may improve that later by indicating receiver's type, or even disambiguating the method based on receiver after the bracket... but that's a topic for another enhancement request.