Is it possible to add support of struct{}?

[ikkeps]

In many cases sets implemented as map[T]struct{}. It would be nice to support it to avoid extra convertion on both server and client sides.

Currently Dispatcher AddFunc panics:

... cannot contain struct without exported fields [struct {}] in the value of map...

I could implement custom GobDecoder/GobDecoder for map[T]struct{}-type in my code, but it would be nice if gorpc supports it.

[ikkeps]

I hacked it like this ikkeps@0b4d2f9
Not sure about this. All tests pass and RPC works.

[valyala]

@Ikeps, thanks for the patch!