rather than the node_label type from the min_cut object.  This
should make the interface much less confusing.

works right.

graphs that are regular grids.

ends of the rows.

cuts on an image the result is a displayable binary image rather than
an image which is super dark and hard to view.

occurred when the model order was larger than the number of variables.

--HG--
rename : dlib/svm/graph_labeler.h => dlib/graph_cuts/graph_labeler.h
rename : dlib/svm/graph_labeler_abstract.h => dlib/graph_cuts/graph_labeler_abstract.h

can set the per class loss to whatever they want.