Added enemy -> brightness skybox

Skybox.h

@@ -6,11 +6,14 @@ class Skybox
 private:
 	float size;
 	std::string folder;
+	float brightness;
+	float targetBrightness;
 public:
 	Skybox(const float &size, const std::string &folder);
 	~Skybox();
 
 	void init();
 	void draw();
+	void update(float deltaTime, int, int);
 	GLuint loadTexture(const std::string &fileName);
 };