Pre-RFC: Explicit overload sets for mixed-arity function calls

I continue to be opposed to anything that just adds a need for overload resolution rules. We have trait resolution rules already; that's enough. I never want to have to think about both trait resolution and overload resolution.

Check zulip -- there are people talking about ways to have a single function delegate to a single trait via a tuple or similar, which seems fine.

In the mean time, you can always just do

draw((point));
draw((x, y));

as ordinary function calls and it's fine.