Get world seed without op permission.

config/seed/config.json

• command: Command to get seed in console
• parser: Parser for the command result

Default config file:

{
    'command': 'seed',
    'parser': 'Seed: [{}]'
}

The default configuration already supports most server software (without plugin/mods).

This plugin was inspired by MCDReforged/Seed

Thanks to @alex3236 for refactoring the code（（