This includes the introduction of the --data-dir parameter instead of the --database.
Both the seed file and the database are stored in the data-dir, the database in sub-folder `database`.
Add a binary crate `swap` that implements two nodes (Alice and Bob). With this
applied we can start up a node for each role and do:
- Bob: Requests current amounts using BTC is input
- Alice: Responds with amounts
- Bob: (mock) get user input to Ok the amounts
... continue with swap (TODO)
