This introduces a lot of duplication between the binary and the
library, but it's okay because this module should only be a temporary
measure until we allow recovery to be handled by the original state
machine.
Also, fix a bug in `xmr_btc::alice::action_generator` caused by the
incorrect assumption that Alice's ability to punish Bob could be
determined before the cancel transaction hits the blockchain.
Also use cosntant backoff retry strategy as opposed to exponential
backoff. This is in case retrying several times quickly causes the
retry intervals to become large enough that the test is very slow
and/or the Bitcoin lock transaction expires.
The current problem occurs on the last message i.e. Bob sending
tx_redeem_encsig to Alice. The action is yielded for Bob to do it, but
Alice appears to never receive it (unconfirmed claim, requires more
logging).
