Move Stats to its own module

Move Stats to its own module and pass it around to the intersection methods to keep track of how many tests and successful intersections there are.

src/objectBox.cc

@@ -53,9 +53,12 @@ Box::SetFar(const Vector3& far)
 
 bool
 Box::DoesIntersect(const Ray& ray,
-                   TVector& t)
+                   TVector& t,
+                   Stats& stats)
     const
 {
+    stats.boxIntersectionTests++;
+
     /*
      * XXX: For now, I'm assuming that all boxes are parallel to the coordinate
      * axes. This is the Kay-Kajiya box intersection algorithm.
@@ -174,8 +177,10 @@ Box::DoesIntersect(const Ray& ray,
     }
 
     /* We have an intersection! */
+    stats.boxIntersections++;
     t.push_back(tNear);
     t.push_back(tFar);
+
     return true;
 }