Sometimes it's really easy to think on Roald Dahl as a children's storyteller - without always remembering that a lot of his stories had some really quite dark undertones. Here, the almost as imaginative Wes Anderson takes four of his shorter stories and works them into this loose compendium of features that takes Dahl's themes and immerses them in his vivid and artistically colourful world of surrealism. Each of these threads is presented by way of a witty and quirkily delivered monologue all under the supervision of a series of personifications attributable to the author himself (Ralph…