fix release date computations, make them mandatory
fix release date computations, make them mandatory

olafurpg/scalameta,MasseGuillaume/scalameta,scalameta/scalameta,xeno-by/scalameta,xeno-by/scalameta,xeno-by/scalameta,scalameta/scalameta,scalameta/scalameta,Dveim/scalameta,MasseGuillaume/scalameta,scalameta/scalameta,DavidDudson/scalameta,olafurpg/scalameta,MasseGuillaume/scalameta,scalameta/scalameta,olafurpg/scalameta,DavidDudson/scalameta