Create a directory `bitcoin` and move into it the following as is with
no code changes:
- src
- Cargo.toml
- contrib
- test_data
- examples
Then do:
- Add a workspace to the repository root directory.
- Add the newly created `bitcoin` crate to the workspace.
- Exclude `fuzz` and `embedded` crates from the workspace.
- Add a contrib/test.sh script that runs contrib/test.sh in each
sub-crate
- Fix the bitcoin/contrib/test.sh script
Recently we (*cough* Tobin) made the `Map` trait private and neglected
to add a public API for combining together two PSBTs. Doing so broke the
`psbt` module.
Pull the merge logic out of the `Map` trait and put it in methods on
each individual type (`Input`, `Output`, `PartiallySignedTransaction`).
Doing so allows for simplification of return types since combining
inputs/outputs never errors.
Use the term 'combine' instead of 'merge' since that is the term used in
BIP 174.