User display name field

Added a "display name" field, which can be NULL. The field can be set
from the user creation form, and is displayed in the list.

database/create-tables.sql

@@ -56,6 +56,7 @@ GRANT SELECT,INSERT,UPDATE,DELETE ON items TO :webapp_user;
 CREATE TABLE users (
 	user_id							INT NOT NULL DEFAULT NEXTVAL('users_user_id_seq'::TEXT),
 	user_email						VARCHAR(256) NOT NULL,
+	user_display_name					VARCHAR(256) ,
 	user_salt						CHAR(8) NOT NULL,
 	user_iterations						INT NOT NULL,
 	user_hash						CHAR(40) NOT NULL,

database/users-functions.sql

@@ -2,14 +2,18 @@
 -- Create a new user
 --
 
-CREATE OR REPLACE FUNCTION users_add( _email TEXT , _salt TEXT , _iters INT , _hash TEXT )
+CREATE OR REPLACE FUNCTION users_add( _email TEXT , _salt TEXT , _iters INT , _hash TEXT , _name TEXT )
 	RETURNS INT
 	LANGUAGE PLPGSQL
 	STRICT VOLATILE SECURITY INVOKER
 AS $users_add$
 BEGIN
-	INSERT INTO users ( user_email , user_salt , user_iterations , user_hash )
-		VALUES ( _email , _salt , _iters , _hash );
+	IF _name = '' THEN
+		_name := NULL;
+	END IF;
+
+	INSERT INTO users ( user_email , user_salt , user_iterations , user_hash , user_display_name )
+		VALUES ( _email , _salt , _iters , _hash , _name );
 	RETURN 0;
 EXCEPTION
 	WHEN unique_violation THEN
@@ -17,5 +21,5 @@ EXCEPTION
 END;
 $users_add$;
 
-REVOKE EXECUTE ON FUNCTION users_add( TEXT , TEXT , INT , TEXT ) FROM PUBLIC;
-GRANT EXECUTE ON FUNCTION users_add( TEXT , TEXT , INT , TEXT) TO :webapp_user;
+REVOKE EXECUTE ON FUNCTION users_add( TEXT , TEXT , INT , TEXT , TEXT ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION users_add( TEXT , TEXT , INT , TEXT , TEXT) TO :webapp_user;