Music Cat Power will be at the Orpheum. Last time Bostonist saw her, she seemed a little plowed and, with her dark glasses, she resembled country singer Ronnie Milsap. Since then, she's been hanging out with Karl Lagerfeld. She's different every time, but the music is always memorable. 7:30 pm. It's cosmopolitan night at the MFA, and we aren't talking about drinks. The uber-sophisticated Keren Ann and Dean & Britta will perform. MFA, Remis Auditorium,......