If an array is passed as the value, the array values are quoted
and then returned as a comma-separated string; this is useful
for generating IN() lists.
{{code: php
$sql = Solar::factory('Solar_Sql');
$safe = $sql->quote('foo"bar"');
$safe == "'foo\"bar\"'"
$safe = $sql->quote(array('one', 'two', 'three'));
$safe == "'one', 'two', 'three'"
}}