1.6.0

• Breaking: Status::Confirming gains max_fee_rate, the chain's, so a
  fee_rate_spike can be shown against it.
• Breaking: Quote gains await_opening_tx, how long after creation the
  server waits for a SwapIn deposit to confirm, and so the expiry to give the
  claim invoice.

Minor

• A SwapIn's Funding expires_at is min_confs + 1 blocks before the claim
  invoice expires, so a deposit made by then confirms in time.
  funding_timeout only caps it and defaults to 24 h, where it was 20 min. A
  claim invoice needs to outlast min_confs + 1 blocks, where it needed
  funding_timeout more.