replacing SCellToMidPoint (deprecated) by CanonicSCellEmbedder
adaptation to the new interface of DSSLengthEstimator
 using Greedy/SaturatedSegmentation; displaying DSSs instead of DSSComputers
replacing SCellToMidPoint (deprecated) by CanonicSCellEmbedder also in 3dCurvatureViewer
 use of the primitive of the segment computer instead of the computer itself in 3dCurveViewer
Merge branch 'PR721' into PR744
Merge pull request #98 from troussil/PR744

Update some tools so that they work with DGtal (after PR #744)