Fix clippy warnings

src/search.rs

 
 enum WorkerMessage {
     PleaseStop,
-    DoBlob(Blob),
+    DoBlob(Box<Blob>),
 }
 
 pub fn par_search<P, F, G>(
         let mut stopped_threads = 0;
 
         // send initial message to each worker thread
-        for thread_id in 0..num_threads {
+        for channel in &chans {
             match reader.next() {
                 Some(Ok(blob)) => {
-                    chans[thread_id].send(WorkerMessage::DoBlob(blob))
+                    channel.send(WorkerMessage::DoBlob(Box::new(blob)))
                         .map_err(|e| format!("{}", e))?;
 
                 },
                     return Err(format!("{}", err));
                 },
                 None => {
-                    chans[thread_id].send(WorkerMessage::PleaseStop)
+                    channel.send(WorkerMessage::PleaseStop)
                         .map_err(|e| format!("{}", e))?;
                     stopped_threads += 1;
                 },
 
             match reader.next() {
                 Some(Ok(blob)) => {
-                    chans[thread_id].send(WorkerMessage::DoBlob(blob))
+                    chans[thread_id].send(WorkerMessage::DoBlob(Box::new(blob)))
                         .map_err(|e| format!("{}", e))?;
                 },
                 Some(Err(err)) => {