Add default argument to prestations.
Remove Prestion (replaced by Column).
Finish removing Prestation
Create real columns for birth and prenom.
Rename AgesCol to AgeCol.
Remove Column.legislative_input boolean: It is not used.
Remove commented code.
In columns, rename _default to default, _dtype to dtype & _func to function.
Add AlternativeFormula (for age & agem).
Improve columns JSON.
Remove annoying print
Fix conflict
Improve Column & Prestation attributes.
Copy default legislation to be able to modify actual legislation without changing the default one.
Add tree of columns.
Add dated legislations validation.
Change order of extra requirements.
Revert latest commit.
Correct package name of PyTables.
Add "begin" and "end" dates to legislations to be able to apply legislations outside their given dates by extending them.