Use FixedStrCol(5) for depcom input variable.
Improve indentation.
Remove useless import.
Remove reform "Impôt sur le revenu (Landais, Piketty, Saez)" from reference decomposition.
Remove obsolete comment and add a prefill_cache method to TaxBenefitSystem to pre-load "zone_apl".
Cleaning reforms and adding plf2015