Newlywed Britney Spears got her brand-new hubby to ink an ironclad prenuptial agreement just days before they got hitched, The New York Post has learned. The deal would protect the pop princess' $100 million fortune in case of another marital disaster. Exact details of the legal document are not known, but it will come in handy if things go the way of Britney's first marriage, which imploded last January after just 55 hours. Britney's decision to keep Kevin Federline on a short leash when it comes to access to her vast fortune is a huge relief for her parents, who'd...