message: Start using cargo-clippy for CI.
diff: // `clippy` is a code linting tool for improving code quality by catching
  -// common mistakes or strange code patterns. If the `clippy` feature is
  -// provided, it is enabled and all compiler warnings are prohibited.
  -#![cfg_attr(feature = "clippy", deny(warnings))]
  -#![cfg_attr(feature = "clippy", feature(plugin))]
  -#![cfg_attr(feature = "clippy", plugin(clippy))]
  -#![cfg_attr(feature = "clippy", allow(inline_always))]
  -#![cfg_attr(feature = "clippy", allow(too_many_arguments))]
  -#![cfg_attr(feature = "clippy", allow(unreadable_literal))]
  -#![cfg_attr(feature = "clippy", allow(many_single_char_names))]
  -#![cfg_attr(feature = "clippy", allow(new_without_default_derive))]
  -#![cfg_attr(feature = "clippy", allow(write_literal))]
  +// common mistakes or strange code patterns. If the `cargo-clippy` feature
  +// is provided, all compiler warnings are prohibited.
  +#![cfg_attr(feature = "cargo-clippy", deny(warnings))]
  +#![cfg_attr(feature = "cargo-clippy", allow(inline_always))]
  +#![cfg_attr(feature = "cargo-clippy", allow(too_many_arguments))]
  +#![cfg_attr(feature = "cargo-clippy", allow(unreadable_literal))]
  +#![cfg_attr(feature = "cargo-clippy", allow(many_single_char_names))]
  +#![cfg_attr(feature = "cargo-clippy", allow(new_without_default_derive))]
  +#![cfg_attr(feature = "cargo-clippy", allow(write_literal))]
  +
  // Force public structures to implement Debug
  #![deny(missing_debug_implementations)]
  