Pass custom marshaller to buffered client.

[makasim]

I am evaluating the replacement of the official fluent client with your package. One thing that is missing is the ability to provide a custom marshaller for the message. I want to convert json bytes to msgpack bytes directly (without marshal\unmarshal) (https://github.com/makasim/jsontomsgp).

I can provide a PR, just want to know if the project is still maintained and PR would be accepted.

[lestrrat]

@makasim Yeah, though it's not being actively developed but I haven't abandoned it.

wrt to your actual feature request, I'm not entirely sure if it fits in a fluent client, but I guess I don't know enough to make a decision at this point, so PoCs/pseudocode/testcases are welcome

[makasim]

Thank you for your reply. I need a way to pass my own marshaller to the client, the rest would be implemented outside the library. Just giving some context, not that important.

I'll send MR later.