Run cargo clippy --fix (#250)

* Run `cargo clippy --fix`
* Run `cargo clippy --all-features --fix`
* Fix other clippy warnings
* cargo fmt

Co-authored-by: Luis Moreno <morenol@users.noreply.github.com>

src/algorithm/neighbour/fastpair.rs

@@ -260,8 +260,8 @@ mod tests_fastpair {
         let distances = fastpair.distances;
         let neighbours = fastpair.neighbours;
 
-        assert!(distances.len() != 0);
-        assert!(neighbours.len() != 0);
+        assert!(!distances.is_empty());
+        assert!(!neighbours.is_empty());
 
         assert_eq!(10, neighbours.len());
         assert_eq!(10, distances.len());
@@ -276,17 +276,13 @@ mod tests_fastpair {
         // We expect an error when we run `FastPair` on this dataset,
         // becuase `FastPair` currently only works on a minimum of 3
         // points.
-        let _fastpair = FastPair::new(&dataset);
+        let fastpair = FastPair::new(&dataset);
+        assert!(fastpair.is_err());
 
-        match _fastpair {
-            Err(e) => {
-                let expected_error =
-                    Failed::because(FailedError::FindFailed, "min number of rows should be 3");
-                assert_eq!(e, expected_error)
-            }
-            _ => {
-                assert!(false);
-            }
+        if let Err(e) = fastpair {
+            let expected_error =
+                Failed::because(FailedError::FindFailed, "min number of rows should be 3");
+            assert_eq!(e, expected_error)
         }
     }
 
@@ -582,7 +578,7 @@ mod tests_fastpair {
         };
         for p in dissimilarities.iter() {
             if p.distance.unwrap() < min_dissimilarity.distance.unwrap() {
-                min_dissimilarity = p.clone()
+                min_dissimilarity = *p
             }
         }