IMPORTANT
This update fixes only one upgrade saving, in order to fix this, follow these steps:

Open the file "kingdoms.db"
Run the SQL command "DROP TABLE kingdom_upgrade_levels;"
This will allow the table to be recreated so multiple upgrades can be saved.

Other Improvements:

Fixed errors with the file getting locked and / or transaction not being opened by using a cache system for loading, so once a certain amount of chunks have been added to the queue or a fixed amount of time has passed, the chunks are loaded from the database.
This appears to have completely fixed the mentioned issues, but make sure to check and report them to me if they continue to occur!

API Chances:

- Changed chunk metadata to transfer when chunks are claimed / unclaimed so you don't have to do it manually yourself.
If you would like to remove the metadata when the chunk ownership is transferred, just listen to the chunk claim and unclaim events and remove them manually.