[+] added use_folders cmake feature if cmake version is greater then 2.8.0

[~] fixed warning in featuers2d under windows (can't generate assignment operator)

modules/features2d/include/opencv2/features2d/features2d.hpp

@@ -1543,6 +1543,9 @@ protected:
     virtual void detectImpl( const Mat& image, vector<KeyPoint>& keypoints, const Mat& mask=Mat() ) const;
 
 private:
+	DynamicAdaptedFeatureDetector& operator=(const DynamicAdaptedFeatureDetector&);
+	DynamicAdaptedFeatureDetector(const DynamicAdaptedFeatureDetector&);
+
     int escape_iters_;
     int min_features_, max_features_;
     const Ptr<AdjusterAdapter> adjuster_;