 By Andrea Shalal GOREE ISLAND, Senegal Reuters - U.S. Treasury Secretary Janet Yellen on Saturday spoke of the unspeakable cruelty and enduring consequences of the trans-Atlantic slave trade, but said she was heartened by signs of progress and renewal in both the United States and Africa. Yellen visited the House of Slaves, a fort built in the late 18th century on Goree Island off the coast of Senegal as a transit point for human beings before they were shipped across the Atlantic, as she co... 