Make build work (#546)

The mbedtls example has caused problem in the main build a number of
times. By making it a standalone `cargo new --bin`, we can keep it in
the source tree as a good example but avoid having it break the main
build.

Also, fix some clippy lints.

src/error.rs

@@ -328,7 +328,7 @@ impl Error {
 }
 
 /// One of the types of error the can occur when processing a Request.
-#[derive(Debug, PartialEq, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum ErrorKind {
     /// The url could not be understood.
     InvalidUrl,

src/header.rs

@@ -62,7 +62,7 @@ impl fmt::Display for HeaderLine {
     }
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Eq)]
 /// Wrapper type for a header field.
 /// <https://tools.ietf.org/html/rfc7230#section-3.2>
 pub struct Header {

src/response.rs

@@ -799,9 +799,9 @@ pub(crate) fn charset_from_content_type(header: Option<&str>) -> &str {
     header
         .and_then(|header| {
             header.find(';').and_then(|semi| {
-                (&header[semi + 1..])
+                header[semi + 1..]
                     .find('=')
-                    .map(|equal| (&header[semi + equal + 2..]).trim())
+                    .map(|equal| header[semi + equal + 2..].trim())
             })
         })
         .unwrap_or(DEFAULT_CHARACTER_SET)

src/stream.rs

@@ -666,7 +666,7 @@ mod tests {
         let mut deadline_stream = DeadlineStream::new(stream, None);
         let mut buf = [0u8; 1];
         for _ in 0..8193 {
-            deadline_stream.read(&mut buf).unwrap();
+            let _ = deadline_stream.read(&mut buf).unwrap();
         }
         let reads = reads.lock().unwrap();
         assert_eq!(reads.len(), 2);

src/test/agent_test.rs

@@ -80,7 +80,7 @@ fn connection_reuse_with_408() {
     // pulls from the pool. If for some reason the timed-out
     // connection wasn't in the pool, we won't be testing what
     // we thought we were testing.
-    let resp = agent.post(&url).send_string("hello".into()).unwrap();
+    let resp = agent.post(&url).send_string("hello").unwrap();
     assert_eq!(resp.status(), 200);
 }
 

src/test/mod.rs

@@ -20,6 +20,7 @@ mod timeout;
 
 type RequestHandler = dyn Fn(&Unit) -> Result<Stream, Error> + Send + 'static;
 
+#[allow(clippy::type_complexity)]
 pub(crate) static TEST_HANDLERS: Lazy<Arc<Mutex<HashMap<String, Box<RequestHandler>>>>> =
     Lazy::new(|| Arc::new(Mutex::new(HashMap::new())));