The `WalletExport` type can still be used as an alias to
`FullyNodedExport` but it has been marked as deprecated and will be
removed in the next release.
Although somewhat convenient to have, coupling the Wallet with
the blockchain trait causes development friction and complexity.
What if sometimes the wallet is "offline" (no access to the blockchain)
but sometimes its online?
The only thing the Wallet needs the blockchain for is to sync.
But not all applications will even use the sync method and the sync
method doesn't require the full blockchain functionality.
So we instead pass the blockchain in when we want to sync.
- To further reduce the coupling with blockchain I removed the get_height call from `new` and just use the height of the
last sync in the database.
- I split up the blockchain trait a bit into subtraits.
Verify the unconfirmed transactions we download against the consensus
rules. This is currently exposed as an extra `verify` feature, since it
depends on a pre-release version of `bitcoinconsensus`.
Closes#352
Thanks to the `ToWalletDescriptor` trait we can also very easily validate the checksum
for descriptors that are loaded from strings, if they contain one. Fixes#20.
Instead of having two traits, `Blockchain` and `OnlineBlockchain` that need
to be implemented by the user, only the relevant one (`OnlineBlockchain`, here
renamed to `Blockchain`) will need to be implemented, since we provide a
blanket implementation for the "marker" trait (previously `Blockchain`, here
renamed to `BlockchainMarker`).
Users of the library will probably never need to implement `BlockchainMarker`
by itself, since we expose the `OfflineBlockchain` type that already does
that and should be good for any "offline" wallet. Still, it's exposed since
they might need to import it to define types with generics.
