Sending to an address inside bitcoin core wallet crashes

[chris-belcher]

Because of this line:

https://github.com/JoinMarket-Org/joinmarket/blob/develop/joinmarket/blockchaininterface.py#L650

getaccounts returns "" when the address isnt contained, but also if the address is in the account "".

If importaddress tries to add an address which is already in there, it seems to crash (TODO check this)

One way to work around this is to surround the importaddress with a try: except JsonRpcError: in python, but that would swallow other errors too.

Another way is to use listaccounts to get all the account names, then getaddressesbyaccount to get all the addresses. This might be slow and overkill, but is probably the only other way.