[BTW Addon] Custom Spawn

• Add support for chinese (thx to Eternity)
• Removed unnecessary comments
• Improve scanning accuracy
• Removed unnecessary biome (Nether, end)
• Add a progression message showing how many attempts have been done during world creation
• Strongholds now generate according to the coords of the custom spawn

The current version is probably more performance hungry, let me know if any issue appears (on discord or in github)