Bump dependency to 1.21, fix some code and remove bstats.

Changed API Version to 1.13 so it supports more versions.
Added metrics.

If you encounter any issues let me know asap.

Fixed some small barely noticeable bugs.

Use /snowballkb:reloadconfig, only works if you are opped.

- An option to add cooldown has been added in the config.
- Message for the cooldown.
- Small bug fixes.

You can now use up to 15 vertical and 15 horizontal, more than 15 is not recommended as it may show errors in console due to Minecraft's mechanics.