* Rather than rely on the legacy notification interface which may be
deprecated in the near future, we’ll now switch to using the
NotificationSever.
* Negative confirmation notifications due to re-orgs are still
unimplemented however.
* Re-orgs are still unhanded.
* RegisterSpendNtfn should perhaps also register directly with the rpc
client instead of pushing the responsibility to the caller.
* Currently depends on the wallet, but that will change in the near
future due to new additions to btcwallet currently under review.
* Re-orgs aren’t intelligently handled yet. To be done along with tests
in a later commit.
