Patch sub-errors to make them backwards compatible

[tcharding]

We would like to alias the DecodeFixedLengthBytesError back into 0.2 and 0.3 as HexToArrayError [0].

During the 1.0 dev cycle we made a few minor API breaks. Turns out we were probably overly savage and the benefits of re-instating the previous API outweigh the maintenance risks we were attempting to mitigate.

Put the InvalidLengthError and InvalidCharError back to how they were when in the 0.3 release.

Done as part of #254

[0] See issue #254 for full context and justification.

[tcharding]

This PR needs to be API addition only, please review accordingly.

[apoelstra]

We have API files here -- can you patch those to make CI happy?

[apoelstra]

Ah, I see, it needs a specific old version of cargo-rbmt. I'll just do it.

You now need to ACK because Github thinks the PR is mine.

[apoelstra]

ACK 828b93d; successfully ran local tests

[tcharding]

I'll just do it.

Thanks. For my understanding. The only way to do this is grab the commit hash from rbmt-version, jump to the maintainer repo, co the commit hash, and install cargo-rbmt. Right? Then unwind it once done. I had to do it on another PR yesterday too so just checking you don't have a better process?

lol, I'm a goose. I will set up a bunch of cargo-rbmt binaries of different versions.

[tcharding]

ACK 828b93d

[apoelstra]

Just needs a release PR now :).

lol, I'm a goose. I will set up a bunch of cargo-rbmt binaries of different versions.

You can just run cargo install cargo-rbmt --git https://git.rust-bitcoin.org/rust-bitcoin/rust-bitcoin-maintainer-tools --rev af3c2868415b17eedc808da6d0589e10b7482660 and then repeat the command with the rust-bitcoin version to "go back".

[tcharding]

Nice, thanks.

[apoelstra]

@tcharding are you willing to make a release PR off master? Then we can double-back and do a new 0.2.x release with the semver trick. This should all be straightforward now that CI is passing there.

[tcharding]

Yep can do.