You want PocketMine-MP Map Export To MineCraft Pocket Edtion World Plugins? I Have it! I'm Crafting Complete! And Complete Compile! You want?
I know, I know. But still people that do not like it, or if you experience a problem with the server, it is a savior is not it?
SimpleWorlds is an official plugin. You can trust to use SimpleWorlds and just use it to export to .dat format of the worlds.