Add getter for fog in Track; it's not used atm but surely it can come in useful... (I added it when investigating bug 8)

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@7878 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/tracks/track.hpp

@@ -317,6 +317,8 @@ public:
     WeatherType   getWeatherType          () const { return m_weather_type; }
     ParticleKind* getSkyParticles         () { return m_sky_particles; }
     
+    bool isFogEnabled() const { return m_use_fog; }
+    
     std::vector< std::vector<float> >     buildHeightMap();
     
 };   // class Track