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/core/test/ocl/test_dft.cpp

@@ -56,7 +56,7 @@ enum OCL_FFT_TYPE
     C2C = 3
 };
 
-namespace cvtest {
+namespace opencv_test {
 namespace ocl {
 
 ////////////////////////////////////////////////////////////////////////////
@@ -185,6 +185,6 @@ OCL_INSTANTIATE_TEST_CASE_P(Core, Dft, Combine(Values(cv::Size(45, 72), cv::Size
                                                )
                             );
 
-} } // namespace cvtest::ocl
+} } // namespace opencv_test::ocl
 
 #endif // HAVE_OPENCL