NEW YORK — The super-exclusive Maidstone Club in East Hampton has been rocked by the death of “caddie master” Kevin Somers, 45, at the nearby home of another club employee, Marc Dern, 35. Suffolk County Police arrested Dern Thursday for allegedly killing the popular employee. Somers, of Amagansett, died “following an altercation” at Dern’s home on Lincoln Ave. at around 10:40 p.m. Feb. 5, according to local reports. Dern was charged with first degree manslaughter. Somers was taken to Stony Brook Southampton Hospital, “where he was pronounced dead,” according to police. The WASPy Maidstone is k…