Manual seeds, FastMarching, SparseField use different state maps
This class holds and (only if required) converts one state map to another
The purpose is primarily the decoupling of the FastMarching from the SparseField
so that a ROI can directly be used for SparseField and FastMarching can run on its own
as separate plugin.
This class has also the ability to create a binary image with the segmentation as output.