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/core/src/gl_core_3_1.cpp

@@ -1,7 +1,7 @@
 #include <string>
 #include <sstream>
 #include "cvconfig.h"
-#include "opencv2/core/core.hpp"
+#include "opencv2/core.hpp"
 #include "gl_core_3_1.hpp"
 
 #ifdef HAVE_OPENGL

modules/core/src/matrix.cpp

@@ -42,7 +42,7 @@
 
 #include "precomp.hpp"
 #include "opencv2/core/gpumat.hpp"
-#include "opencv2/core/opengl_interop.hpp"
+#include "opencv2/core/opengl.hpp"
 
 /****************************************************************************************\
 *                           [scaled] Identity matrix initialization                      *

modules/core/src/opengl_interop.cpp

@@ -41,7 +41,7 @@
 //M*/
 
 #include "precomp.hpp"
-#include "opencv2/core/opengl_interop.hpp"
+#include "opencv2/core/opengl.hpp"
 #include "opencv2/core/gpumat.hpp"
 
 #ifdef HAVE_OPENGL

modules/core/src/precomp.hpp

@@ -47,7 +47,7 @@
 #include "cvconfig.h"
 #endif
 
-#include "opencv2/core/core.hpp"
+#include "opencv2/core.hpp"
 #include "opencv2/core/core_c.h"
 #include "opencv2/core/internal.hpp"