Fixed compilation errors: removed using namespace from hpp file. This led to pulling cv::ACCESS_MASK to global namespace where conflict with the same name in 'windows.h'

apps/traincascade/boost.cpp

@@ -1,4 +1,18 @@
 #include "opencv2/core.hpp"
+#include "opencv2/core/utility.hpp"
+
+using cv::Size;
+using cv::Mat;
+using cv::Point;
+using cv::FileStorage;
+using cv::Rect;
+using cv::Ptr;
+using cv::FileNode;
+using cv::Mat_;
+using cv::Range;
+using cv::FileNodeIterator;
+using cv::ParallelLoopBody;
+
 
 #include "boost.h"
 #include "cascadeclassifier.h"