Updated the coordinate system in /spawn service for consistency.

Author: jarvisschultz

turtlesim/src/turtle_frame.cpp

@@ -176,7 +176,7 @@ std::string TurtleFrame::spawnTurtle(const std::string& name, float x, float y,
     }
   }
 
-  TurtlePtr t(new Turtle(ros::NodeHandle(real_name), turtle_images_[index], QPointF(x, y), angle));
+  TurtlePtr t(new Turtle(ros::NodeHandle(real_name), turtle_images_[index], QPointF(x, height_in_meters_ - y), angle));
   turtles_[real_name] = t;
   update();