Main module headers are moved 1 level up

e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

modules/flann/include/opencv2/flann.hpp

@@ -46,7 +46,7 @@
 #ifdef __cplusplus
 
 #include "opencv2/core/types_c.h"
-#include "opencv2/core/core.hpp"
+#include "opencv2/core.hpp"
 #include "opencv2/flann/flann_base.hpp"
 #include "opencv2/flann/miniflann.hpp"
 

modules/flann/include/opencv2/flann/miniflann.hpp

@@ -45,7 +45,7 @@
 
 #ifdef __cplusplus
 
-#include "opencv2/core/core.hpp"
+#include "opencv2/core.hpp"
 #include "opencv2/flann/defines.h"
 
 namespace cv

modules/flann/include/opencv2/flann/timer.h

@@ -32,7 +32,7 @@
 #define OPENCV_FLANN_TIMER_H
 
 #include <time.h>
-#include "opencv2/core/core.hpp"
+#include "opencv2/core.hpp"
 
 namespace cvflann
 {