Bob Moyer reviews a book that, both author and reviewer make clear, is not an autobiography. And yet… Reviewed by Robert P. Moyer STILL PICTURES: On Photography and Memory. By Janet Malcom. Farrar, Straus & Giroux. 155 pages. $26. Janet Malcolm wrote many New Yorker articles as well as many books about interesting subjects—Gertrude Stein, Chekov,…