.hgignore: add vendor tree composer.json: new packages plugins/thunderbird_labels/thunderbird_labels.php: change hook and RFC822 use wrt whitelisting to avoid deprecated stuff index.php: commented debugging hooks others: new releases of vendor packages?

-- Updates from version 0.4.2

DROP INDEX users_username_id_idx;
ALTER TABLE users ADD CONSTRAINT users_username_key UNIQUE (username, mail_host);
ALTER TABLE contacts ALTER email TYPE varchar(255);

TRUNCATE messages;