exo6: add the full implementation. Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
exo6: add constructor and some sanity checks to Chiffre and Variable classes. Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
exo6: add the basic code structure with the right class hierarchy Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>