Merge pull request #40 from kerautret/sdpViewer

Sdp viewer
Merge branch 'master' of github.com:DGtal-team/DGtalTools
Merge branch 'master' of github.com:DGtal-team/DGtalTools
add vectors display in 3dSDPViewer
Changelog and readme
Merge branch 'master' into 3DSDPViewerAdds
Merge pull request #126 from kerautret/3DSDPViewerAdds

3dSDP viewer adds