Changes

• Permissions-based XP booster system
• New formula configuration for flexible next XP values

Ex: 'leveltools.booster.2' will give a 2x booster to anyone with the permission Ex: 'leveltools.booster.1.5' will give a 1.5x booster to anyone with the permission Ex: '100 + {current_level} * 100' is the default formula in config.yml

Please update your configurations to support this new value!