Introduced fadeIn and fadeOut functionality via scripting.

include/openspace/rendering/renderengine.h

@@ -90,6 +90,9 @@ public:
     // This is a temporary method to change the origin of the coordinate system ---abock
     void changeViewPoint(std::string origin);
 
+	//temporaray fade functionality
+	void startFading(int direction, float fadeDuration);
+
 private:
 	void storePerformanceMeasurements();
 
@@ -108,6 +111,9 @@ private:
 	void generateGlslConfig();
 
 	float _globalOpactity;
+	float _fadeDuration;
+	float _currentFadeTime;
+	int _fadeDirection;
 
 	bool _visualizeABuffer;
 	ABufferVisualizer* _visualizer;