TORONTO — Canada's main stock index gained almost 300 points Wednesday on widespread market strength, while U.S. stocks rose after a mixed trading day. The S&P/TSX composite index closed up 290.49 points at 25,569.84. In New York, the Dow Jones industrial average was up 317.24 points at 44,873.28. The S&P 500 index was up 23.60 […]