Remove future re-exports (#133)

These types were moved around in
https://github.com/tokio-rs/axum/pull/130 but re-export from their old
location for backwards compatibility.

This removes the re-exports.

src/routing.rs

@@ -1,5 +1,6 @@
 //! Routing between [`Service`]s.
 
+use self::future::{BoxRouteFuture, EmptyRouterFuture, RouteFuture};
 use crate::{
     body::{box_body, BoxBody},
     buffer::MpscBuffer,
@@ -27,11 +28,6 @@ use tower_http::map_response_body::MapResponseBodyLayer;
 
 pub mod future;
 
-// for backwards compatibility
-// TODO: remove these in 0.2
-#[doc(hidden)]
-pub use self::future::{BoxRouteFuture, EmptyRouterFuture, RouteFuture};
-
 /// A filter that matches one or more HTTP methods.
 #[derive(Debug, Copy, Clone)]
 pub enum MethodFilter {