THREE ERAS, ONE MISSED OPPORTUNITY Brownstone collapses under unfocused, baffling staging Catherine Butterfield's Brownstone (2008) is built around a solid, even enticing idea: we have three couples, each occupying the same second-floor apartment in a Manhattan brownstone during three eras"1930s, the 1970s, and the turn of the 21st century. Instead of three separate acts in… The post Theater Review: BROWNSTONE (Ope…