Run cargo clippy --fix

[rukai]

This PR runs cargo clippy --fix and commits the changes it made.
You can reproduce the same changes by running that command yourself.

I have reviewed the changes and not seen anything controversial in there.
This includes:

• minor performance improvements - reduced allocations, clones etc.
• minor simplifications to the code - removal of needless &, removal of needless closures.
• I was a little surprised by the addition of const blocks in the thread_local! macros, but those were introduced by this lint https://rust-lang.github.io/rust-clippy/master/index.html#/thread_local_initializer_can_be_made_const which checks out.

[rukai]

I reran cargo clippy --fix to pull in any new fixes added since june.
I added in a separate commit in case you had previously partially reviewed the changes.

One of the new changes was fixing of this lint: https://rust-lang.github.io/rust-clippy/master/index.html#doc_lazy_continuation
clippy --fix resolved the issue by adding more > but I think that in reality this block should use quote blocks which looks much better.

Before:

After:

The other new change is uncontroversial.

Hoping you'll be able to take a look at this PR as well.

[astonbitecode]

Thanks!