Gladstone-Dale law rerfactive index profile

In this MR I have created a refractive index profile that uses the Gladstone-Dale law to calculate that through the density profile.

corsika/detail/media/GladstoneDaleRefractiveIndex.inl

@@ -18,9 +18,7 @@ namespace corsika {
                                                                        Point const point, Args&&... args)
       : T(std::forward<Args>(args)...)
       , seaLevelRefractiveIndex_(seaLevelRefractiveIndex)
-      , earthSurface_(point)
-      , seaLevelDensity_(this->getMassDensity(earthSurface_)) {}
-//      , ratio_((1. - seaLevelRefractiveIndex_) / (seaLevelDensity_ * cube(1_m) / 1_kg)) {}
+      , seaLevelDensity_(this->getMassDensity(point)) {}
 
   template <typename T>
   inline double GladstoneDaleRefractiveIndex<T>::getRefractiveIndex(Point const& point) const {