fix: Stop using displaydoc

[upbqdn]

Motivation

Rust beta now contains a new lint (rust-lang/rust#120393) which produces a bunch of compilation warnings in the CI. They all come from displaydoc (https://github.com/yaahc/displaydoc) which has an open PR (yaahc/displaydoc#47) containing a trivial fix for the issue but hasn't been merged in more than two months.

Solution

• Remove displaydoc.
• Impl fmt::Display manually for types that used to use displaydoc.
• Unrelated:
  • There's another new lint that checks the alignment in lists in comments, so I fixed that.

Tests

The solution doesn't need tests.

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.

[upbqdn]

An alternative solution would be to use the branch of displaydoc containing the fix until it gets merged.

[arya2]

This looks good, thank you!

An alternative solution would be to use the branch of displaydoc containing the fix until it gets merged.

That may cause issues when we're publishing crates for the next version of Zebra, I like that we're removing a scarcely used dependency, though displaydoc also looks very nice if we want to add it back later and use it more.

[Manishearth]

Displaydoc 0.2.5 was published (yaahc/displaydoc#51), if you wish to go back to mainline displaydoc.