Add patch-based data loading with probabilistic oversampling.

[jakubMitura14]

Success when

given the size of the 3D patch by the user algorithm after data loading will crop or pad the supplied image to meet the set size criterion. The part of the image where the label is present should be selected more frequently than the areas without during cropping, the probability that the area with some label indicated on segmentation mas will be chosen will equal p (0-1) where p is supplied by the user