Iceland — where the tectonic plates of Europe and America rub — is a hot destination these days. Here, a quick stop-over on your flight to Europe turns into a bonus vacation. You can luxuriate in a steamy hot mineral spring amid a vast lava flow, charge over glacial-runoff rivers to desolate perches made to order for a Game of Thrones scene, marvel at the sleek lines of a modern cathedral standing like an exclamation point in the capital city, and enjoy meals that could rival the finest feasts i