fix: more refactoring

src/math/distance/euclidian.rs

@@ -21,7 +21,7 @@ mod tests {
     use super::*;    
 
     #[test]
-    fn measure_simple_euclidian_distance() {
+    fn squared_distance() {
         let a = vec![1., 2., 3.];
         let b = vec![4., 5., 6.];