In what could be his biggest personal accomplishment ever, Mr. Met is going to the Mascot Hall of Fame. Yesterday, the Mascot Hall of Fame named Mr. Met a member of its 2007 class along with the San Antonio Coyote. The Post, which is thumping its chest with the news, talked to Mets spokesman Jay Horowitz, "We're thrilled at what he does. He does a lot of good charity work, the kids love him, and......