THE parents of Madeleine McCann have penned a heartbreaking tribute to mark the 18th anniversary of her disappearance. Clinging onto hope of finding their daughter, Kate and Gerry thanked those who have supported them and kept Madeleine in their thoughts. PAKate and Gerry vowed to ‘leave no stone unturned’ as they continue their fight for the truth[/caption] AFPMadeleine was just three years old when she disappeared in 2007[/caption] FacebookKate and Gerry shared this tribute to thei