DHT service for FlylinkDC++.

DB scheme:

CREATE TABLE `dht_info` (
    `cid` CHAR(39) NOT NULL,
    `ip` VARCHAR(15) NOT NULL,
    `port` SMALLINT(5) UNSIGNED NOT NULL,
    `conn_count` SMALLINT(5) UNSIGNED NOT NULL DEFAULT '0',
    `user_agent` VARCHAR(256) NULL DEFAULT NULL,
    `live` TINYINT(3) UNSIGNED NOT NULL DEFAULT '0',
    `last_time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (`cid`)
) ENGINE=InnoDB;

ALTER TABLE dht_info ADD INDEX i_dht_info_live (live)