Extreme Clippy for existing Crate

See how we get started with Extreme Clippy on a new Crate.

Enabled all the lints in Cargo.toml:

[lints.clippy]
cargo        = { priority = -1, level = "deny" }
complexity   = { priority = -1, level = "deny" }
correctness  = { priority = -1, level = "deny" }
nursery      = { priority = -1, level = "deny" }
pedantic     = { priority = -1, level = "deny" }
perf         = { priority = -1, level = "deny" }
restriction  = { priority = -1, level = "deny" }
style        = { priority = -1, level = "deny" }
suspicious   = { priority = -1, level = "deny" }

I had to run this command 3 time to disable all the lints that were violated by the Rust Digger code-base that can be found here.

cargo clippy 2>&1 | grep https://rust-lang.github.io/rust-clippy/master/index.html | sed 's/^.*#//' | sort | uniq | xargs -I % echo '% = "allow"' >> Cargo.toml