Media representation of disabled people is challenging to get right — too saccharine, and you’re veering towards inspiration porn, too maudlin, and you’re implying that a disabled life might not be a life worth living. “Ibelin,” the newest documentary from “The Painter and the Thief” filmmaker Benjamin Ree, strikes a poignant balance, acknowledging the ways that physical disability can limit a life while showing how one complex man expanded his world nonetheless.