Merge branch 'develop' into feature/scenegraphloader

Conflicts:
	src/abuffer/abuffer.cpp
	src/rendering/renderengine.cpp
	src/scene/scene.cpp

include/openspace/rendering/model/renderablemodel.h

@@ -62,6 +62,7 @@ private:
 
 	modelgeometry::ModelGeometry* _geometry;
 
+	float _alpha;
 	glm::dmat3 _stateMatrix; 
 
 	std::string _source;

include/openspace/rendering/planets/renderableplanet.h

@@ -67,6 +67,7 @@ private:
     planetgeometry::PlanetGeometry* _geometry;
     properties::BoolProperty _performShading;
 	properties::IntProperty _rotation;
+	float _alpha;
 
 	glm::dmat3 _stateMatrix;
 

include/openspace/rendering/renderable.h

@@ -69,6 +69,8 @@ public:
     virtual void update(const UpdateData& data);
 
 	bool isVisible() const;
+	bool hasTimeInterval();
+	bool getInterval(double& start, double& end);
 
 protected:
     std::string findPath(const std::string& path);
@@ -79,6 +81,9 @@ private:
 	
     PowerScaledScalar boundingSphere_;
     std::string _relativePath;
+	std::string _startTime;
+	std::string _endTime;
+	bool _hasTimeInterval;
 };
 
 }  // namespace openspace