Description:
------------
If the code in the callback of the consume function throws an exception, PHP will 
lock up. This is caused by the amqp_consume ignoring exceptions and continuing to 
try to call the function.

This happens with both 1.0.3 and 1.0.4

Test script:
---------------
<?php
$cnn = new AMQPConnection();  $cnn->connect();
$ch  = new AMQPChannel($cnn);
$ex  = new AMQPExchange($ch);  $ex->setName('exchange-' . time()); $ex->setType(AMQP_EX_TYPE_FANOUT); $ex->declare();
$q   = new AMQPQueue($ch);    $q->setName('queue-' . time());     $q->declare();
$q->bind($ex->getName(), 'routing.*');
$ex->publish('message1', 'routing.1'); $ex->publish('message2', 'routing.2');
$count = 0;
function consumeThings($message, $queue) {
        global $count; $count++;
        echo $message->getBody() . "-" . $message->getRoutingKey() . "\n";
        if ($count == 2) {
                global $ex,$q;
                $ex->delete(); $q->delete();
                throw new Exception( "Dead" );
        }
        return true;
}
try{ $q->consume("consumeThings"); }catch( Exception $e ){ print $e->getMessage(); }
/*--EXPECT-- message1-routing.1 message2-routing.2 Dead */


Expected result:
----------------
message1-routing.1 
message2-routing.2
Dead


Actual result:
--------------
message1-routing.1 
message2-routing.2

and then hang.