[Fix] fix wrong values of type boolean

[albertcht]

Hi there,

When you try to batch insert/update a boolean-type value, a false value will be converted to empty string which leads to failure in mysql query.

$final[$field][] = 'WHEN `' . $index . '` = \'' . $val[$index] . '\' THEN ' . $value . ' ';

So in this pull request, I convert the boolean values to 1 or 0 in mysql_escape function to prevent this error.

if (is_bool($fieldValue)) { return (int) $fieldValue; }

All the best~