GLOBAL MARKETS-Shares cool after best week of the year

* Stocks dip but head for best week of the year* Risk sentiment softens after first Ebola case in NY* U.S. and euro zone economic data positive* Oil on track for first weekly gain in five weeksBy Marc JonesLONDON, Oct 24 (Reuters) - Global stock markets were heading for their best week of the year on Friday following reassuring company results, encouraging data from the world&aposs biggest economi