CONWAY, N.H. - Democrat John Edwards yesterday changed course and announced that he would accept public campaign financing, which was once the standard approach for presidential candidates but has in the last two elections become a last refuge among those unable to raise enough from private donors. The move, announced just before the end of the third-quarter fund-raising period on Sunday, allows Edwards to take up to about $21 million in matching funds in exchange for abiding by a primary-season spending limit of $50 million. But the move is likely to be perceived as an acknowledgment that he has been...