Select Error in BillLine.php

Hi.
In BillLine.php the lines

$crit.=" and workDate>=\"".$this->startDate."\"";
$crit.=" and workDate<=\"".$this->endDate."\"";

in function save and in function delete use double quote for date values. This is not allowed by postgres.
The same query fails when you do not enter start/ end date in form, as query is executed before validating mandatory field.
I fixed in this way

if ($this->startDate) $crit.=" and workDate>'" . $this->startDate . "'";
if ($this->endDate) $crit.=" and workDate<'" . $this->endDate . "'";
Best regards