message: rename passthru arg to make it clearer
  the clippy args passthrough only allows one arg per instance of the flag
  and does not resplit on spaces, as such it should be more obvious to the
  user that you need to specify the flag once per clippy argument.
diff: @@ -79,8 +79,8 @@ pub fn cli() -> App {
  .hidden(true),
  )
  .arg(
  - Arg::with_name("clippy-args")
  - .long("clippy-args")
  + Arg::with_name("clippy-arg")
  + .long("clippy-arg")
  .help("Args to pass through to clippy, implies --clippy")
  .hidden(true)
  .multiple(true)
  