Basketball legend Shaquille O'Neal has listed his Isleworth estate for $28 million. The 31,000-square-foot mansion at 9927 Giffin Court in Windermere, FL is where "a world of luxury awaits," according to the Premier Sotheby's International Realty exclusive listing. "Privately situated on 3 acres overlooking tranquil Lake Butler, this magnificent custom home sits behind the gates…