Added
- imgproc.matchHist(): "Modify image intensities to match the
histogram of a reference image" by
[rcasero](https://github.com/rcasero)
- imgproc.imfuse(): "Composite of two images" by
[rcasero](https://github.com/rcasero)
- testdata/*.png: Stereo cloud images with ROI masks (left_mask.png,
left.png, right_mask.png, right.png) by
[rcasero](https://github.com/rcasero)