This update brings two cool features to the plugin!
You can now disable the backpacks when certain placeholders are set to false!
This is useful for situations where you want to prevent the backpacks from being open while in combat.

Additionally, for performance, admins can now set a cooldown on how often backpacks can be opened/closed, by adding a cooldown on them.

Extra bug fixes:
- Sacks will now refuse to be tampered with while in a lockdown
- Fixed a couple unused imports in the JAR

API Changes:
- Added SackModifyEvent
- Removed @API annotation (in case anyone was using it)