more work on singleton-based DB

api/index.php

backend.php

classes/db.php

classes/db/mysql.php

classes/db/pgsql.php

classes/sessionhandler.php

include/autoload.php

include/db.php

include/errorhandler.php

include/functions.php

include/sessions.php

index.php

opml.php

prefs.php

public.php

register.php

update.php

update_daemon2.php