The fate of some of The Simpsons’ most popular characters appears to be in limbo. Harry Shearer, who voices characters including Ned Flanders, Mr. Burns, Dr. Hibbert, Rev. Lovejoy, Principal Skinner and others, announced on Twitter that he is leaving the animated sitcom because of a contract dispute. Shearer is one of The Simpsons’ founding cast members who began working on the show back in 1989. In his tweets, he suggested that a contractual limitation on working on additional projects was part of the reason for his departure. As The Daily Beast notes, it’s not the first time Shearer has publicly taken issue with Simpsons producers. In 2011, the show cut the cast’s salaries despite Shearer’s public negotiation efforts. Fox recently greenlit two more seasons of the long-running comedy …