Despite warnings of potentially dire consequences from lenders, federal bank and thrift regulators have gone ahead with a proposed guidance that would establish new qualification standards for lenders making nontraditional mortgage loans. The long-awaited proposed guidance, issued last week by the Federal Reserve Board, the Office of the Comptroller of the Currency, the Federal Deposit Insurance Corp., the National Credit Union Administration, and the Office of Thrift Supervision would set standards for the way that…