ts: refactor OpenCV tests

- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers

modules/imgproc/test/test_thresh.cpp

@@ -41,8 +41,7 @@
 
 #include "test_precomp.hpp"
 
-using namespace cv;
-using namespace std;
+namespace opencv_test { namespace {
 
 class CV_ThreshTest : public cvtest::ArrayTest
 {
@@ -420,3 +419,5 @@ void CV_ThreshTest::prepare_to_validation( int /*test_case_idx*/ )
 }
 
 TEST(Imgproc_Threshold, accuracy) { CV_ThreshTest test; test.safe_run(); }
+
+}} // namespace