Miami Worldcenter cleared its second-to-last governmental hurdle on Thursday. Despite objections from some project critics, Miami commissioners voted unanimously to grant preliminary approval to zoning changes and an agreement that would allow the developers of the 17-acre mixed-use project to begin construction. The developers said they will build 1,083 condos, a 1,800-room hotel with a 600,000 square-foot convention center and a 765,000 square-foot shopping mall anchored by Macy’s and Bloomingdale’s from Northeast Sixth to 11th streets between Northeast Second and North Miami avenues.