[BOUNDARY ERRATA] geoBoundaries Belize border missing major islands

[zygoballus]

The geoBoundaries border for Belize currently only includes 2 islands, Ambergris Caye and Turneffe Atoll. At the very least it needs to include Caye Caulker, which is a major populated island. Other islands that are significant include Lighthouse Reef, Glover's Reef, Tobacco Caye, and Sarstoon Island.