Gets the format details for a particular format ID.
$dfid: A date format ID.
A date format object with the following properties:
function system_get_date_format($dfid) {
return db_query('SELECT df.dfid, df.format, df.type, df.locked FROM {date_formats} df WHERE df.dfid = :dfid', array(
':dfid' => $dfid,
))
->fetch();
}