prop340: Tweaks, clarifications, open questions.
This MR makes the following changes in proposal 340 (packed and fragmented messages):
- Clarify
RELAY_EARLY
implications. (I think this reflects our current discussions, but please let me know if it doesn't.) - Add a network parameter to control the number of permitted RELAY_EARLY messages. (It turns out that we didn't have one.)
- Note a problem with using this format with Conflux: we don't currently handle the possibility of a message (like RELAY_CONFLUX_SWITCH) being sent in the middle of fragments from other messages. I think we need to solve this, or we need to say that fragments of a single message can't be sent across multiple circuits.