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/objdetect/perf/perf_cascadeclassifier.cpp

@@ -1,5 +1,5 @@
 #include "perf_precomp.hpp"
-#include <opencv2/imgproc/imgproc.hpp>
+#include <opencv2/imgproc.hpp>
 
 using namespace std;
 using namespace cv;