[DGFiP] Allow using -kN with N between 1 and 4 (useful for DGFiP tests) + some cleanup

[ddeclerck]

Note: updated expected test results ; they changed because of the removal of calls to M.sauve_base_XXX (these are are only used when a corrective computation calls a primitive computation, but we are not in this case here)

[denismerigoux]

This needs rebasing but good for me!