Add a better skin algorithm

[yuripourre]

Color region:
A single pixel is not enough to determine if a pixel has skin color or not.

False positives:
Also is possible that a certain color is a pixel in an image but is not an image in another image.

References:
https://www.hindawi.com/journals/mpe/2018/5754604/

[yuripourre]

Bayesian Network libraries:
https://github.com/amidst/toolbox
https://github.com/yuripourre-forks/Java-Naive-Bayes-Classifier