AMSTERDAM (Reuters) - Conservative policymakers slammed the European Central Bank's fresh stimulus measures on Friday, voicing doubts about the need and the effectiveness of a package that could consume most of the bank's remaining firepower. Facing a protracted slowdown, the ECB cut rates deeper into negative territory on Thursday and agreed to relaunch bond purchases with no scheduled end-date, a move that divided the rate-setting Governing Council.Although no vote was taken, sources with..