The historical short stories in Emma Donoghue’s new collection, “Astray,” wander across centuries and continents, but they actually don’t stray far from this Irish-born writer’s preoccupations with captivity, sexual predation, prostitution and the grip of parenting. Donoghue is best known for her previous book, the heart-stopping novel, “Room,” about a young woman who gives birth and raises a small son while held captive in a bunker for seven years by a rapist.