Support extracting URL params multiple times (#15)

Useful when building higher order extractors.

src/lib.rs

@@ -601,7 +601,7 @@
     clippy::match_like_matches_macro,
     clippy::type_complexity
 )]
-#![forbid(unsafe_code)]
+#![deny(unsafe_code)]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 #![cfg_attr(test, allow(clippy::float_cmp))]
 
@@ -614,6 +614,8 @@ use tower::Service;
 #[macro_use]
 pub(crate) mod macros;
 
+mod util;
+
 pub mod body;
 pub mod extract;
 pub mod handler;