Toward the end of 1990, you couldn't get away from Simpsons merchandise- from posters, to pajama sets, to pencil toppers- mostly featuring Generation-X's very first mainstream media icon, Bart Simpson. You see, before "The Simpsons" became obsessed with Homer's gradual decline into retardation, the show's initial protagonist was skateboarding prankster Bart- the country's first take on their next generation. And those savvy Simpsons writers seemed to have nailed it. While Bart's driving characte