Out here in the woods, at the end of not one but two dirt roads, in a shack equipped with a picture of the Dalai Lama, a high-speed data line and a copy of Thoreau’s “Civil Disobedience,” Amazon’s dream of dominating the publishing world has run into some trouble. Douglas Preston, who summers in this coastal hamlet, is a best-selling writer — or was, until Amazon decided to discourage readers from buying books from his publisher, Hachette, as a way of pressuring it into giving Amazon a better deal on e-books. So he wrote an open letter to his readers asking them to contact Jeff Bezos, Amazon’s chief executive, demanding that Amazon stop using writers as hostages in its negotiations. The letter, composed in the shack, spread through the literary community.