Display 2D and 3D image primitive in Display3D (now only in DisplayViewer)

Adding  2D and 3D image primitives in Display3D.
The display follows the classic display with also DrawWithDisplay3DModifier :
----
Viewer3D view;
view << image2D;
viewer <<  DGtal::UpdateImagePosition(1, DGtal::Display3D::xDirection, 50.0, 0.0, 0.0);
viewer << DGtal::UpdateImageData<Image2D>(0, sliceImageZ, 0, 0, 10);
----
(with image2D and image3D can be a DGtal::ImageContainerBySTLVector)
It contains also examples and doc update but to test you need to merge the branch of PR #595 and now Travis should failed.
To test you can also just test on an already merged:
https://github.com/kerautret/DGtal/tree/masterForVisu
A simple slice tools is also given on a special branch:
https://github.com/kerautret/DGtalTools/tree/masterForVisu