Would you want to read a 17 million-word diary? What about watching someone write it? “The diary of Arthur Crew Inman, a notorious recluse and one of Boston’s great eccentrics, has already been transformed into a play: Camera Obscura by Lorenzo DeStefano. Tonight the chamber opera company Intermezzo premieres The Inman Diaries, an opera by Thomas Oboe Lee based on the play and on Inman’s colossal diary.”