Fixed null error

- Rewritten for better performance
- added 1.21.5 support

Improved cleanerwhen destroying hopper

Added fix - corrupted hopper when removing last block
Added auto-clean when removing hopper

I would like to apologize for non-working plugin, here is fixed version, I made critical mistake and I was forced to rewrite whole plugi. Give us new chance, thanks! Everything should be fine now!

Fixed permission error when clicking on hopper.

Fixed null error when click on air

- Players are not allowed to click on inventory on empty slot (air)
- Fixed %block% variable in confirm menu metas
- Fixed slow reaction when adding blocks (reload was required before apply changes, it's fixed now
- Player's are now able to place chests and trapped chests above the hopper with sneak
- fixed message when adding new blocks
- Destroying hopper will cause database.yml to be removed from -> when you place hopper again, you will must to configure it again
- Fixed empty hopper message not receive