By Mike Walters Luke Littler was fitted with a Green Jacket after landing his fourth title in as many months in Graz last night. Warrington’s boy wonder beat Joe Cullen 8-4 in the final at the Austrian Darts Open to claim his second trophy on the European Tour in his debut season on the professional circuit. ‘Luke the Nuke’ has now won titles in Bahrain, Belgium, Austria and on the floor in Britain – as well as sitting top of the Premier League. The noisy 2,500-strong crowd adopted Littler as one of their own and he said: “I thought the fans in Belgium were great, but these guys were somethin…