Add overloaded cv::PCACompute() that returns also the eigenvalues. Useful for Java and Python OpenCV where PCA is not available.

Fixed Matx::solve function for non-square matrixes (#11904)

      - Changing the contrast and brightness of an image!
      - Operations with images

Temporary object lifetime must be greater than pointer usage.

use vload3 for half3 or float3 input vector reading,
also check read position to see if it exceed input width
Signed-off-by: Li Peng <peng.li@intel.com>

Add a note in the documentation about Mat::ones and mat::eye. With multi-channels type (e.g. CV_8UC3), only the first channel is treated.

"custom layers" feature will not work properly in these builds.

use cv::AutoBuffer::data() to get data pointer