After seven agonizing years, The Knife is finally back with a new album, Shaking the Habitual. The Swedish siblings—Karin Dreijer Andersson, aka Fever Ray, and her brother, Olof Dreijer—have once again brought together their unorthodox trademarks: tribal percussion, early techno rhythms, atonal vocals, and lyrical social commentary. That’s what happens when you build an album from a zither and a bedspring…