Previously the function may cause some unsafe issue. It is fixed now by introducing a template parameter.

Also cv::, cv::gpu:: and cv::ocl:: namespace prefixes can be safely omitted
inside CV_ENUM and CV_FLAGS

RadiusMatch for HammingDist cannot pass yet.

The program would crash if release is called twice.

Match template in ocl module now can be utilized with dft based
convolve. Note this feature needs OpenCV to be built with clAmdFft
library.