[SkyDetect] add example of creating mask, add empty SPixel class
[SPixel] add basix methods add/getAdj() add/getPix()
[SkyDetect] add initSPixelsFromLabels() method
[SPixel] add some getters and setters.
[SkyDetect] update initSPixelsFromLabels() to ctreate SPixel with name greater by 1, so any spixel cant have got name 0. Add initSPixelAdj() method to create adjency vector for every spixels. Now it can only do masked patern image, but only in CV_8UC1 type, but we need CV_16UC1 masked image to compute adjency in future.