Refactor Redirect API (#741)

Changed the redirect types to be from the `redirect` module:

- `reqwest::RedirectPolicy` is now `reqwest::redirect::Policy`
- `reqwest::RedirectAttempt` is now `reqwest::redirect::Attempt`
- `reqwest::RedirectAction` is now `reqwest::redirect::Action`

Changed behavior of default policy to no longer check for redirect loops
(loops should still be caught eventually by the maximum limit).

Removed the `too_many_redirects` and `loop_detected` methods from
`Action`.

Added `error` to `Action` that can be passed any error type.

Closes #717

src/lib.rs

@@ -119,9 +119,9 @@
 //!
 //! ## Redirect Policies
 //!
-//! By default, a `Client` will automatically handle HTTP redirects, detecting
-//! loops, and having a maximum redirect chain of 10 hops. To customize this
-//! behavior, a [`RedirectPolicy`][redirect] can used with a `ClientBuilder`.
+//! By default, a `Client` will automatically handle HTTP redirects, having a
+//! maximum redirect chain of 10 hops. To customize this behavior, a
+//! [`redirect::Policy`][redirect] can be used with a `ClientBuilder`.
 //!
 //! ## Cookies
 //!
@@ -175,7 +175,7 @@
 //! [get]: ./fn.get.html
 //! [builder]: ./struct.RequestBuilder.html
 //! [serde]: http://serde.rs
-//! [redirect]: ./struct.RedirectPolicy.html
+//! [redirect]: crate::redirect
 //! [Proxy]: ./struct.Proxy.html
 //! [cargo-features]: https://doc.rust-lang.org/stable/cargo/reference/manifest.html#the-features-section
 
@@ -237,7 +237,6 @@ pub use self::into_url::IntoUrl;
 /// - native TLS backend cannot be initialized
 /// - supplied `Url` cannot be parsed
 /// - there was an error while sending request
-/// - redirect loop was detected
 /// - redirect limit was exhausted
 pub async fn get<T: IntoUrl>(url: T) -> crate::Result<Response> {
     Client::builder().build()?.get(url).send().await
@@ -279,7 +278,6 @@ if_hyper! {
         multipart, Body, Client, ClientBuilder, Request, RequestBuilder, Response, ResponseBuilderExt,
     };
     pub use self::proxy::Proxy;
-    pub use self::redirect::{RedirectAction, RedirectAttempt, RedirectPolicy};
     #[cfg(feature = "tls")]
     pub use self::tls::{Certificate, Identity};
 
@@ -293,17 +291,9 @@ if_hyper! {
     //#[cfg(feature = "trust-dns")]
     //mod dns;
     mod proxy;
-    mod redirect;
+    pub mod redirect;
     #[cfg(feature = "tls")]
     mod tls;
-
-    #[doc(hidden)]
-    #[deprecated(note = "types moved to top of crate")]
-    pub mod r#async {
-        pub use crate::async_impl::{
-            multipart, Body, Client, ClientBuilder, Request, RequestBuilder, Response,
-        };
-    }
 }
 
 if_wasm! {