Silence compiler and clippy warnings…

[ImmemorConsultrixContrarie]

Description

… by doing what compiler and clippy say to do.

Motivation and Context

I don't like seeing warnings.

How Has This Been Tested?

cargo +nightly clippy && cargo test

Checklist:

• Acknowledged that by making this pull request I release this code under an MIT/Apache 2.0 dual licensing scheme.
• My code follows the code style of this project.
• If my change required a change to the documentation I have updated the documentation accordingly.
• I have updated the content of the book if this PR would make the book outdated.
• I have added tests to cover my changes.
• My code is used in an example.

[ImmemorConsultrixContrarie]

#249, #250, #251, #252 and #255 failed CI due to compiler warnings (which this PR silenced), not actual problems. For the last two of them it is even worse, because it is failed beta that cancelled almost all other tests, not just failed nightly.
Could someone do something with warnings (merge this PR, write and merge another PR, etc.) and rerun CI for those fails?

[TomGillen]

These PRs are only failing CI on nightly (which we allow). New checks added to nightly clippy can happen without warning and will cause spurious CI failures. We should probably remove clippy from the nightly builds in CI.

[TomGillen]

bors r+

[bors]

Build succeeded:

• Tests (macos-latest, beta)
• Tests (macos-latest, stable)
• Tests (ubuntu-latest, beta)
• Tests (ubuntu-latest, stable)
• Tests (windows-latest, beta)
• Tests (windows-latest, stable)