Added WorldInfo mappings
Added WorldInfo mappings

Added fields and methods for net.minecraft.world.storage.WorldInfo in
mappings.conf.

kenzierocks/SpongeVanilla,CodeKingdomsTeam/SpongeVanilla,CodeKingdomsTeam/SpongeVanilla,DDoS/SpongeVanilla,DDoS/SpongeVanilla,kenzierocks/SpongeVanilla