NEW YORK (Reuters) - Harvard historian Niall Ferguson posted an "unqualified apology" on his personal blog on Saturday after saying that British economist John Maynard Keynes did not care about the future because he was gay and had no children. The comments were "as stupid as they were insensitive," Ferguson wrote. While speaking at a conference of investors in California on Thursday, Ferguson was asked to comment on Keynes' observation that "in the long run, we are all dead." He described his response as "off the cuff," and not part of his formal presentation. ...