Superflat Dimensions

Big update!

• Moved the world down to y=0, slimes now spawn!
• Added more underground features (geodes, fossils, dungeons!)
• Moved the nether down to y=0 as well.
• Changed bodies of water to be 1 block deep.
• Added "clay disks" to bodies of water for aesthetics.
• Changed depth to make surface cave biomes really rare.
• Strongholds are now properly enclosed.
• Completely refactored the datapack structure.
• Fixed a bug where ruined portals would spawn floating/buried in the nether.
• Fixed bug that caused wooded badlands dirt/coarse dirt to not form.
• Fixed a bug where holes generated in frozen ocean biomes.
• Fixed bug where mineshafts didn't have minecart chests.
• Fixed a bug where the swamp water wasn't generating.
• Fixed a bug where glow berries weren't generating in lush caves.