By Manya Saini (Reuters) -Visa’s tepid forecast for current-quarter revenue growth on Thursday eclipsed a market-beating earnings report that was powered by customers swiping their cards for big purchases during the holiday shopping period and robust travel. Even so, executives at Visa struck an optimistic tone over the outlook for spending across the year. Severe winter storms that hit the U.S. have weighed on volumes at the start of the year, CFO Chris Suh said in an interview with Reuters, but added that the company is not worried about any broader impact and expects it to get smoothed out …