NEW YORK — Republican Donald Trump promised on Monday to be "fair, but firm" toward the estimated 11 million immigrants living in the United States illegally, a shift in tone that raised questions on whether he's backtracking from previous pledges to push for mass deportations.The billionaire businessman, whose hard-line approach to immigration and fierce rhetoric propelled him to the GOP presidential nomination, insisted that he's not "flip-flopping" on the divisive issue as [...]