8-year-old painting prodigy is new art world star                                                       By JILL LAWLESS, Associated Press Writer                    Jill Lawless, Associated Press Writer                                   Fri Aug 13, 8:54 am ET                                                    HOLT, England – He's Britain's most  talked-about young artist. His paintings fetch hefty sums and there's a  long waiting list for his eagerly anticipated new works.  It has all happened so quickly — he's still  getting used to the spotlight — and Kieron Williamson fidgets a little  when he's asked to share his thoughts on art.  "Cows are the easiest thing to paint," said Kieron, who has just turned 8. "You don't have to worry about doing so much detail."  Horses, he says, are "a lot harder. You have  to get their legs right, and you have to make their back legs much  bigger than their front....