Flush deallocation queue before calling map/unmap

* Error in the documentation for cv::getRectSubPix. #9788
The function name is corrected to GetRectSubPix since, it uses the notation
of src, dst and center. Also added the number of channel assertion criteria.

* Error in the documentation for cv::getRectSubPix. #9788
Replace dst with patch in the formula, reverted function name to
getRectSubPix, removed BorderTypes comment line due to no explicit call
to the function found.

* Error in the documentation for cv::getRectSubPix. #9788
Replace dst with patch in the formula, reverted function name to
getRectSubPix, removed BorderTypes comment line due to no explicit call
to the function found.

- reorder path HINTS to avoid conflicts with other LAPACK libraries
- add extern "C" { } to avoid generation of C++ symbols

ts(misc): support tables exporting in markdown format

Add camera/video/image input for C++ DNN object detection samples. Add nice display and computation time.

OpenCL SURF implementation is unstable

Incorrect "total" buffer size calculated in StdMatAllocator::allocate() due wrong step values.