Atlantic city’s Planning Board has advanced revisions to the Marina District Redevelopment Plan, setting the stage for City Council to decide later this month whether to approve wide-ranging changes that could reshape more than 90 acres of long-underused waterfront land.The board voted to endorse an amended plan that would loosen development rules on the site – including a 70-acre tract between Harrah’s Resort Atlantic City and the Borgata Hotel Casino & Spa – and open the door to a full mixed-use neighborhood with new homes, commercial space and improved circulation for pedestrians and cyclists.