Fix CME for BlockDataManager

CME would occur when saving on shutdown

Fix ItemUtils#toString and fromString

• Should now properly work for all items
• Previously would not work for banners and some other complex items like bee hives with bees inside them

Fixed issue which would cause DataBlocks to be deleted erroneously

• Chunks flagged as modified would not be unflagged when saved
• This would cause modified chunks that were unloaded when saveAll is called to be deleted

Improve performance for saving/unloading data for BlockDataManager

• Previously would wait for a loading task to complete before unloading, this could cause severe lag in some cases
• Now cancels loading task instead

Fix NPE for BlockDataManager

• NPE would occur when loading a chunk, then unloading it, then loading it again and attempting to interact with DataBlocks

Add support for comments via ConfigManager

• Add comments to config fields with the repeatable @Comment annotation
• Only supported in 1.18.1 and above, since there was no support for comments in spigot's config library prior to that

Minor improvements

• Fix rare error which would happen when opening SQLite connections on some platforms
• Make DataBlocks remove keys mapped to null values

Complete rewrite of BlockDataManager

• Can now be backed by either PDC or SQLite
• Can now retrieve data asynchronously
• Can now automatically load data asynchronously as chunks are loaded
• To migrate from an old SQLite database, call BlockDataManager#migrate, only available for SQLite-backed managers

Fix primitive wrapper conversions for collections and maps in ConfigManager

• Map<Double, V> would sometimes have issues if some keys in config were formatted like ints, this is now fixed

Fix StringIndexOutOfBoundsException

6.4.0.1

Fix StringIndexOutOfBoundsException