The National Trust, Britain's heritage and nature conservation charity, said on Thursday that specialists had started work re-chalking the UK 's "largest and most iconic chalk hill figure," the Cerne Abbas Giant.  The roughly 55-meter (180-feet) tall chalk giant carved into a hillside overlooking Cerne Abbas in Dorset in southwest England is a standout figure of the landscape and renowned landmark, not least because it's such an anatomically faithful rendering of a naked and clearly excited club-wielding man. The outline is prone to the elements, though, and requires regular renewal to prevent it from fading.…