Description:
------------
Using SphinxClient::setLimits($offset, $limit, $max_matches, 
$cutoff).

Documentation states the $max_matches is optional.

Complete newbie that I am, looking at the source 
$max_matches is auto set to 0, by definition unlimited. 
Using this value will result in an error:

per-query max_matches=0 out of bounds (per-server 
max_matches=1000)

If $max_matches is left out by the user, it should be set to 
whatever value is in sphinx.conf.

Or perhaps I got this all wrong?

Reproduce code:
---------------
<?php
$s = new SphinxClient;
$s->setLimits(0, 20);
$result = $s->query('test');
echo $s->getLastError();
?>

Expected result:
----------------
As the documentation states 
(http://php.net/manual/en/sphinxclient.setlimits.php) the 
limit is optional, and should be set to whatever the 
sphinx.conf is set to if $max_matches is left out by the user.