Modernising the code, improving images

src/Cxx/SimpleOperations/DistanceBetweenPoints.cxx

 #include <vtkMath.h>
- 
-int main(int, char *[])
+
+int main(int, char*[])
 {
   // Create two points.
   double p0[3] = {0.0, 0.0, 0.0};
   double p1[3] = {1.0, 1.0, 1.0};
- 
+
   // Find the squared distance between the points.
   double squaredDistance = vtkMath::Distance2BetweenPoints(p0, p1);
 
   // Take the square root to get the Euclidean distance between the points.
-  double distance = sqrt(squaredDistance);
- 
+  double distance = std::sqrt(squaredDistance);
+
   // Output the results.
   std::cout << "SquaredDistance = " << squaredDistance << std::endl;
   std::cout << "Distance = " << distance << std::endl;