Bill Murray, speaking to a crowd of publishers and booksellers, talked of his new status as a writer. “And in order to give you a feeling for the book that I’ve written, I have come completely unprepared,” he said. Murray, co-author of the golf book and memoir “A Cinderella Story,” said at this weekend’s BookExpo America in Los Angeles, “I became a writer back in 1999. I had approximately, uh, the rest of the month to finish it.” He joked about his inability to meet deadlines, apologized for exceeding his allotted speaking time and offered encouragement to all the independent booksellers in his own special way. “I’ve never gone to the Internet and sat down and read anything,” he said. “But I’ve never gone to the Internet and shoplifted, either.”