We model the getting of amounts as a network behaviour even though conceptually
it is a protocol. Refine/refactor the code a bit to make this more obvious.
- Use `Amounts` instead of `Messenger`
We only ever connect to a single peer, update peer tracker to reflect this. This
is a single patch because the handling of the two network behaviours is a
intertwined.
- Only track one peer connection
- Track the peer id and the multiaddr of the counterparty
- Emit an event for connection established on Alice's side as well as Bob's side
Add a binary crate `swap` that implements two nodes (Alice and Bob). With this
applied we can start up a node for each role and do:
- Bob: Requests current amounts using BTC is input
- Alice: Responds with amounts
- Bob: (mock) get user input to Ok the amounts
... continue with swap (TODO)
