Allow relabeling without conn comp in rav export
Allow relabeling without conn comp in rav export

Raveler export used connected components so that neither superpixels
nor segments would be disjoint. This is not very important for more
recent modes of proofreading, so it has become optional (which enables
the use of segmentations that don't have zeros between the segments).

jni/gala,janelia-flyem/gala,stuarteberg/ray,jni/ray