This PR introduces optimization for connectedComponents() and connectedComponentsWithStats() functions by adding a new state-of-the-art CCL algorithm (i.e. Spaghetti Labeling) as described in Spaghetti Labeling: Directed Acyclic Graphs for Block-Based Connected Components Labeling, IEEE Transactions on Image Processing. Performance comparisons can be found in the paper and in the YACCLAB repository. Tests have been updated accordingly and additional test cases for statistics calculation have been added.

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