Iteration03 - review fixes

(cherry picked from commit d413fef3)

src/main/java/cz/muni/fi/pb162/project/geometry/Circle.java

@@ -24,8 +24,7 @@ public class Circle {
      * This is a default constructor with default parameters.
      */
     public Circle() {
-        this.center = new Vertex2D(0, 0);
-        this.radius = 1;
+        this(new Vertex2D(0, 0), 1);
     }
 
     public Vertex2D getCenter() {

src/main/java/cz/muni/fi/pb162/project/geometry/Vertex2D.java

@@ -40,7 +40,7 @@ public class Vertex2D {
      */
     @Override
     public String toString() {
-        return format("[%s, %s]", Double.valueOf(x).toString(), Double.valueOf(y).toString());
+        return format("[%s, %s]", x, y);
     }
 
     /**