Americans’ doom and despair about the economy is mounting. In fact, by one measure, the public is more depressed than they’ve ever been in the postwar era. The University of Michigan has been surveying American consumers’ sentiment since all the way back in 1952 — and their result from last month was the lowest level they’ve ever found. A CNN survey this week found deepening doubts about the core of the American dream. Asked whether most people can get ahead if they’re willing to work hard, 47 p