other: add clippy lints to deny todo and unimplemented (#1085)

src/bin/main.rs

@@ -1,6 +1,8 @@
 #![warn(rust_2018_idioms)]
+#![deny(clippy::todo)]
+#![deny(clippy::unimplemented)]
 #![deny(clippy::missing_safety_doc)]
-#[allow(unused_imports)]
+#[allow(unused_imports)] // TODO: Deny unused imports.
 #[cfg(feature = "log")]
 #[macro_use]
 extern crate log;

src/lib.rs

@@ -6,9 +6,10 @@
 //! bottom, refer to [here](https://clementtsang.github.io/bottom/stable/).
 
 #![warn(rust_2018_idioms)]
+#![deny(clippy::todo)]
+#![deny(clippy::unimplemented)]
 #![deny(clippy::missing_safety_doc)]
-// TODO: Deny unused imports.
-#[allow(unused_imports)]
+#[allow(unused_imports)] // TODO: Deny unused imports.
 // Only used for builds not intended for release.
 #[cfg(feature = "log")]
 #[macro_use]