1-based option for "Pixel" Transformer classes

[CPBridge]

The "Pixel" transformer classes in the spatial module work with 0-based pixel indices, as is natural for python programmers. However when working with other DICOM objects, it is common to encounter 1-based pixel indices (e.g. the 2D coordinates used in ANN objects). There should be a way to support these conveniently, either with options on the existing classes, or new classes.