One of the subprime market’s largest players, Ameriquest Mortgage, is retooling its retail origination platform as part of a cost-saving push that it says will help it expand into new market segments – including the Alt A space. Last week, Ameriquest abruptly laid off close to 4,000 loan officers and processors while shuttering more than 200 retail branches. Going forward, the privately-held California-based firm, which has built one of the most recognizable brands in…