Distance transform propagate labels

[bogovicj]

Working toward propagating a set of labels while performing a distance transform.

transformPropagateLabels(distance, labels, distanceType)

behaves identically to transform with respect to the distance argument, but also
modifies the input labels such that the label at any given point is given by the label
with the closes distance to that point (where the distances are given by

For example, for 1D inputs distance and labels given by:

distance = [ 9.0, 9.0, 1.0, 9.0, 9.0, 9.0,  1.5, 9.0 ]  
labels   = [   4,   2,   1,   0,   8,   0,    2,   0 ]

will modify labels to be:

labels   = [   1,   1,   1,   1,   1,   2,    2,   2 ]

[axtimwalde]

Done