DETROIT — Picking up right where they left off, Donald Trump, Ted Cruz and Marco Rubio barked out fresh insults at each other in a Republican presidential debate Thursday night that also featured a crude sexual reference from Trump — and an healthy dose of policy, too. Cruz and Rubio, who earlier had devoted considerable debate time to throwing sharp elbows at one another, were relentless in training their fire on Trump. Rubio justified his attacks on Trump by saying the billionaire businessman had “basically mocked everybody” over the past year.