cd40ae7f19 Improve Message constructors (Tobin C. Harding)
Pull request description:
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.
### Note
The original PR conflate 2 separate issues, the `Message` constructor naming clarity issue and the upgrade difficulty issue, PR is now only a solution to the first. The second will be done as a separate PR.
ACKs for top commit:
apoelstra:
ACK cd40ae7f19
Tree-SHA512: 4e5aeccf15cca95073f4c3a518b9e1f54f0e33c92c45dfecd1daa31d052022cd28c71bb6df6cff8a6548993e3e22788f11cd2633214ab5a580c753e66d2ea749