Add the hit function to get the closest non negative hit, and add some mecanisme to test that properly and report when no valid hit occur.

source/include/intersect.h

@@ -23,6 +23,7 @@ public:
     void add(Intersection i);
     int count() { return this->num; };
     Intersection operator[](const int p) { return this->list[p]; }
+    Intersection hit();
 };
 
 #endif //DORAYME_INTERSECT_H