Instead of blindly using the `sighash_type` set in a psbt input, we
now only sign `SIGHASH_ALL` inputs by default, and require the user to
explicitly opt-in to using other sighashes if they desire to do so.
Fixes#350
The lint `manual_map` is new so we cannot explicitly allow it and
maintain backwards comparability. Instead, allow all lints for
`get_utxo_for` with a comment explaining why.
Idiomatic Rust uses lowercase for acronyms for all characters after the
first e.g. `std::net::TcpStream`. PSBT (Partially Signed Bitcoin
Transaction) should be rendered `Psbt` in Rust code if we want to write
idiomatic Rust.
Use `Psbt` instead of `PSBT` when aliasing the import of
`PartiallySignedTransaction` from `bitcoin` library.
