Added setRowValue to sql.inc.php

Counterpart to getRowValue, which also users `database`.`table` instead
of `table` FROM `database`.
More functions for verifications

Backend: dbUserVerification[Add/Delete]Code.
Public: publicVerifyUser, publicSendWelcomeEmail.
getUserRoleDefault added to settings
Added verification page JS

If user_id and code are provided in the url, it sends a request to
publicVerifyUser and updates with the result.