When a child reaches 10 or 11 years old there is often a moment when relatives begin to notice a slight withdrawal. It is almost audible, like a tiny door shutting. Someone whose reactions have previously been direct now takes a small detour – but who knows where?That moment, less often chronicled than adolescent tempests, usually coincides with new, bigger school. It can bring quiet heartache for parents (who can complain about a child’s greater independence?) but the new Pixar animation Inside Out makes of it a lively, complex drama equally weighted for adult comprehension and youthful entertainment. In short, it is a cracker, set sometimes “out” in a computer-generated version of reality for Riley, 11, who is moving with her parents from the familiar ice-hockey-