A central Illinois farm is not responsible for injuries to a woman who fell into a bonfire at a sorority barn dance.A state appeals panel ruled last week that the large fire, its embers and surrounding debris were an “open and obvious” threat that barred claims under premises liability law.The plaintiff, an Illinois State University student attending a sorority function at the rural McLean County farm in September 2012, alleges she fell into the embers while posing for a photo. She suffered first-, second- and …