negentropy: Consider pulling wanted messages #20
Description
Currently we only use half of the negentropy discovered information. When we know that a remote node needs something we have we push it. This is good enough, as the protocol progresses further remote nodes will discover that we want something and push it to us.
But is it more efficient to directly ask for needed messages as soon as we know we need them instead of relying on further negentropy exchange? The meshtastic network is very unreliable, maybe it is better to act directly as soon as we know we want something. We could also retry these requests.
Alternatively we could explore not sending negentropy IdLists. This needs more research, but it might be possible to not send the IdLists in some situations. I think the standard negentropy protocol does not send them in one direction because the client manages both "want" and "have" and the server doesn't get these lists.
Related to #19