GLOBAL MARKETS-Euro and oil resume fall; stocks slip on weak data

* ECB chief says ready to act on low inflation* Euro brushes against $1.20* Stocks pressured by weak manufacturing readings(Updates prices, adds comment)By Rodrigo CamposNEW YORK, Jan 2 (Reuters) - The euro started out the new year on a weak note against the U.S. dollar on Friday, continuing the slide that saw the single currency finish out 2014 at a 29-month low, on expectations that the European