Use the more terse `hashes` by way of the `package` field in the
manifest.
Allows us to remove the ugly feature alias "bitcoin-hashes" ->
"bitcoin_hashes" and removes all the bother with the underscore.
Why did we not think of this 2 years ago?
Observe:
- The word "hash" can be a verb or a noun, its usage in function names
is therefore at times ambiguous.
- The function name `from_slice` gives no indication as to what the
slice input is.
Improve Message constructors by doing:
- Add a constructor `Message::from_digest` that takes a 32 byte array as
input.
- Rename `Message::from_slice` to `Message::from_digest_slice`
(deprecate `from_slice` and add `from_digest_slice`)
- Improve the docs while we are at it.
Currently we have a few problems with our feature gating, attempt to
audit all feature gating and fix it by doing:
1. Do not enable features on optional dependencies (`rand` and
`bitcoin-hashes`) in dev-dependencies, doing so hides broken feature
gating in unit tests.
2. Do not use unnecessary feature combinations when one feature enables
another e.g. `any(feature = "std", feature = "alloc")`.
3. Enable "std" from "rand-std" and "bitcoin-std" (and fix features
gating as for point 2).
4. Clean up code around `rand::thread_rng`, this is part of this patch
because `thread_rng` requires the "rand-std" feature.
5. Clean up CI test script to test each feature individually now that
"rand-std" and "bitcoin-hashes-std" enable "std".
Run the command `cargo +nightly fmt` to fix formatting issues.
The formatter got confused in one place, adding an incorrect
indentation, this was manually fixed.
With the introduction of Schnorr signatures, exporting a `Signature`
type without any further qualification is ambiguous. To minimize the
ambiguity, the `ecdsa` module is public which should encourage users
to refer to its types as `ecdsa::Signature` and `ecdsa::SerializedSignature`.
To reduce ambiguity in the APIs on `Secp256k1`, we deprecate several
fucntions and introduce new variants that explicitly mention the use of
the ECDSA signature algorithm.
Due to the move of `Signature` and `SerializedSignature` to a new module,
this patch is a breaking change. The impact is minimal though and fixing the
compile errors encourages a qualified naming of the type.