[Enhancement/code already provided] Experience level limit

class:

net/playavalon/mythicdungeons/dungeons/Dungeon
public boolean meetsRequirements(Player player)

add code：

        int requiredLevel = Integer.parseInt(this.config.getString("Requirements.level"));
        int playerLevel = player.getLevel();
        if (playerLevel < requiredLevel) {
            LangUtils.sendMessage((CommandSender)player, "instance.requirements.player-level", Integer.toString(requiredLevel));
            return false;
        }