merged mdrollette fixes for PR php-amqplib#2

Author: videlalvaro

PhpAmqpLib/Channel/AbstractChannel.php

@@ -117,7 +117,7 @@ public function next_frame()
           MiscHelper::debug_msg("waiting for a new frame");
         }
 
-        if($this->frame_queue != null) {
+        if(!empty($this->frame_queue)) {
             return array_pop($this->frame_queue);
         }
 

PhpAmqpLib/Wire/AMQPWriter.php

@@ -33,7 +33,7 @@ private static function bytesplit($x, $bytes)
         while ($bytes > 0) {
             $b = bcmod($x,'256');
             $res[] = (int)$b;
-            $x = bcdiv($x,'256',0);
+            $x = bcdiv($x,'256', 0);
             $bytes--;
         }