FOREX-US dollar falls, but on pace for eight straight weeks of gains; yuan slumps
(Recasts, adds analyst comment, bullets, byline, NEW YORK dateline, FX table; updates prices) * U.S dollar index 8-week winning streak, longest since 2014 * But dollar index weekly gains getting smaller -analyst * China's onshore yuan hits 2007 low * Canadian dollar rises vs US unit after Canadian j...