Support using a bitcoind that doesn't have the wallet enabled

[stevenroose]

No description provided.

[stevenroose]

On second thought, there are other reasons why bwt won't work on a wallet-less node, but maybe this change isn't too bad after all? Or we can print a better error when this returns None to inform the user that you need to compile bitcoind with the wallet enabled or so?

[shesek]

In its current form, bwt heavily relies on the bitcoind wallet functionality to track wallet activity. bwt derives the wallet addresses, imports them into the wallet, builds some additional indexes on top of what bitcoind provides, and maintains the gap limit by importing more addresses as it becomes necessary.

I would like to eventually add additional backends to bwt, like client-side block filtering or the esplora http api. This would require going through transactions and searching for relevant inputs/outputs on bwt's side, which also would make it easier to implement a wallet-less bitcoind rpc as a backend (or through the p2p protocol, even).

I'm hoping to start tackling this soon (tm). nakamoto seems very promising at the basis for a client-side filtering backend.

For now, it would definitely be great if it printed a more useful error message. Would you like to look into that or should I?