The numerous tor conditional compile flags were removed by
extracting transport creation to the main statement. A tor
transport is created if Alice specifies a tor port using the CLI.
The hardcoded configuration was replaced with CLI
configuration options. CLI based config was chosen
over a config file as it does not access and clutter
the user's file system. By CLI options depend on whether
the program is run in Alice or Bob mode.
Before this patch Bob is not sending message 3. This is because we are not
polling Bob's swarm correctly. To fix it we can just mimic the other NB's and
bubble up an event when Bob receives message 3 response from Alice, this way we
can `await` upon this event which triggers polling, making Bob's swarm send the
message.
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).
Unfortunately, I had to put the wrap the swarm in Alice's `Network`
struct in an `Arc<Mutex<T>>` in order to be able to use `backoff` to
control the retry mechanism. This is because the stream of events
cannot be turned into a `SharedFuture` (unlike Bob's).
It would be good to find an alternative solution.
Alice does not respond with anything when receiving message 2 from Bob. We don't
want to leave Bob's request/response protocol waiting so send an empty response
back.
It looks like the compiler can ascertain that `message0` will be
initialised by the time we use it, so it doesn't need to be an
`Option` and it doesn't need to be declared as mutable.
In order for Alice to complete the handshake she needs to transition to state 3,
for this she needs message 2 from Bob.
Send `bob::Message2` to Alice and transition to `State3` - completing the
handshake.
