Fix OpenCL's wrong output of calcOpticalFlowPyrLK function's output vector of err. Improve err's precison of the calcOpticalFlowPyrLK OpenCL function and add the relative test.

Issue 8647: Updated doc for cv::matchTemplate to reflect current support for methods when mast template is supplied.

Added default parameters for minDisparity, numDisparities and blockSize. This fixes a bug where SGBM::load would not compile.

Spell correction

Corrected the spelling which was used in explanation for parameters.

from linked targets of base modules

This updates the public headers to use _Nm instead of _N in templates
since _N is defined by the widely used ctype.h.