Removed unused computation of CoG (#737)

* Removed unused computation of CoG
In the lift drag plugin there were a few lines of code used to compute the center of gravity of the respective link. Since the variables themselfes are unused I propose to remove them.

* Revert "Removed unused computation of CoG"

This reverts commit 97378945e26c16ce3341090c4b453731b2aeadd9.

Reverted changes to undo the formatting.

* Removed unused computation of CoG
In the lift drag plugin there were a few lines of code used to compute the center of gravity of the respective link. Since the variables themselfes are unused I propose to remove them.

src/liftdrag_plugin/liftdrag_plugin.cpp

@@ -381,12 +381,6 @@ void LiftDragPlugin::OnUpdate()
   // compute moment (torque) at cp
   ignition::math::Vector3d moment = cm * q * this->area * momentDirection;
 
-#if GAZEBO_MAJOR_VERSION >= 9
-  ignition::math::Vector3d cog = this->link->GetInertial()->CoG();
-#else
-  ignition::math::Vector3d cog = ignitionFromGazeboMath(this->link->GetInertial()->GetCoG());
-#endif
-
   // force about cg in inertial frame
   ignition::math::Vector3d force = lift + drag;