Stocks fell in Europe and Asia and the dollar strengthened on Thursday after the Federal Reserve took an upbeat view of the world’s largest economy and signaled it was on track to raise interest rates this year. The stronger dollar helped push U.S. oil prices to six-year lows and weighed on the price of gold. The Fed, after a two-day policy meeting, also said it would be “patient” and would take international developments into account in deciding when to raise borrowing costs — a reference some in the markets saw as meaning any hike could be delayed.