More parser work: fixed a few bugs with [[intlinks]] in headers, a bug that caused the paragraph parser to return an empty string, and added a warning/backup-and-restore for when a render stage returns an empty string.
ALTER TABLE {{TABLE_PREFIX}}session_keys ADD COLUMN key_type smallint NOT NULL DEFAULT 0;
UPDATE {{TABLE_PREFIX}}session_keys SET key_type = 2 WHERE auth_level > 2;
ALTER TABLE {{TABLE_PREFIX}}users ADD COLUMN user_dst varchar(11) NOT NULL DEFAULT '0;0;0;0;60';
ALTER TABLE {{TABLE_PREFIX}}users ADD COLUMN user_rank_userset smallint NOT NULL DEFAULT 0;