Remove some needless double-references

The compiler will immediately de-reference these borrows so there's not
point in including the ampersand.

src/client.rs

@@ -242,7 +242,7 @@ impl Iterator for ClientConnection {
             let connection_header = rq
                 .headers()
                 .iter()
-                .find(|h| h.field.equiv(&"Connection"))
+                .find(|h| h.field.equiv("Connection"))
                 .map(|h| h.value.as_str());
 
             let lowercase = connection_header.map(|h| h.to_ascii_lowercase());

src/request.rs

@@ -143,7 +143,7 @@ where
     // finding the transfer-encoding header
     let transfer_encoding = headers
         .iter()
-        .find(|h: &&Header| h.field.equiv(&"Transfer-Encoding"))
+        .find(|h: &&Header| h.field.equiv("Transfer-Encoding"))
         .map(|h| h.value.clone());
 
     // finding the content-length header
@@ -154,15 +154,15 @@ where
     } else {
         headers
             .iter()
-            .find(|h: &&Header| h.field.equiv(&"Content-Length"))
+            .find(|h: &&Header| h.field.equiv("Content-Length"))
             .and_then(|h| FromStr::from_str(h.value.as_str()).ok())
     };
 
     // true if the client sent a `Expect: 100-continue` header
     let expects_continue = {
         match headers
             .iter()
-            .find(|h: &&Header| h.field.equiv(&"Expect"))
+            .find(|h: &&Header| h.field.equiv("Expect"))
             .map(|h| h.value.as_str())
         {
             None => false,
@@ -175,7 +175,7 @@ where
     let connection_upgrade = {
         match headers
             .iter()
-            .find(|h: &&Header| h.field.equiv(&"Connection"))
+            .find(|h: &&Header| h.field.equiv("Connection"))
             .map(|h| h.value.as_str())
         {
             Some(v) if v.to_ascii_lowercase().contains("upgrade") => true,

src/response.rs

@@ -134,7 +134,7 @@ fn choose_transfer_encoding(
     let user_request = request_headers
         .iter()
         // finding TE
-        .find(|h| h.field.equiv(&"TE"))
+        .find(|h| h.field.equiv("TE"))
         // getting its value
         .map(|h| h.value.clone())
         // getting the corresponding TransferEncoding
@@ -254,23 +254,23 @@ where
         let header = header.into();
 
         // ignoring forbidden headers
-        if header.field.equiv(&"Connection")
-            || header.field.equiv(&"Trailer")
-            || header.field.equiv(&"Transfer-Encoding")
-            || header.field.equiv(&"Upgrade")
+        if header.field.equiv("Connection")
+            || header.field.equiv("Trailer")
+            || header.field.equiv("Transfer-Encoding")
+            || header.field.equiv("Upgrade")
         {
             return;
         }
 
         // if the header is Content-Length, setting the data length
-        if header.field.equiv(&"Content-Length") {
+        if header.field.equiv("Content-Length") {
             if let Ok(val) = usize::from_str(header.value.as_str()) {
                 self.data_length = Some(val)
             }
 
             return;
         // if the header is Content-Type and it's already set, overwrite it
-        } else if header.field.equiv(&"Content-Type") {
+        } else if header.field.equiv("Content-Type") {
             if let Some(content_type_header) = self
                 .headers
                 .iter_mut()
@@ -348,12 +348,12 @@ where
         ));
 
         // add `Date` if not in the headers
-        if !self.headers.iter().any(|h| h.field.equiv(&"Date")) {
+        if !self.headers.iter().any(|h| h.field.equiv("Date")) {
             self.headers.insert(0, build_date_header());
         }
 
         // add `Server` if not in the headers
-        if !self.headers.iter().any(|h| h.field.equiv(&"Server")) {
+        if !self.headers.iter().any(|h| h.field.equiv("Server")) {
             self.headers.insert(
                 0,
                 Header::from_bytes(&b"Server"[..], &b"tiny-http (Rust)"[..]).unwrap(),

src/util/mod.rs

@@ -34,7 +34,7 @@ pub fn parse_header_value(input: &str) -> Vec<(&str, f32)> {
 
             for p in params {
                 if p.trim_start().starts_with("q=") {
-                    if let Ok(val) = f32::from_str(&p.trim_start()[2..].trim()) {
+                    if let Ok(val) = f32::from_str(p.trim_start()[2..].trim()) {
                         value = val;
                         break;
                     }