BISSAU, Guinea-Bissau (AP) — Guinea-Bissau will vote on Sunday in a presidential election marked by political and ethnic tensions with President Umaro Sissoco Embalo seeking a second term that would make him the nation’s first leader elected to successive terms. The presidential and parliamentary elections come at a critical time in West Africa where democracy has recently been challenged by disputed elections that analysts say could embolden militaries that have forcefully taken power in