[Cake] adding "rtt" support correctly

[Dave Taht]

is it up to me to do that, add it to the API, and break it for some other stuff?
(I'd meant to do that last week, but you all know what I got sucked
into instead)

jonathon, I would like you to commit or not commit to delivering the
dual hash idea next week. Otherwise, I think we should submit cake to
net-next for review as it stands after the rtt change enters.

-- 
Dave Täht
Do you want faster, better, wifi? https://www.patreon.com/dtaht