Use legislation accessors (instead of _P) for mini functions.
Don't fail in _ars when there is no children.
Rename and rearrange various sections of imput_variables
Add scripts to use Impôts simulator.
Add debug_all option when creating simulations.
Add support for formulas traceback.
Merge branch 'master' of https://github.com/openfisca/openfisca-france