Changed a few strstr to strpos for consistency w performance guidelines and to mirror EE2.
diff --git a/system/libraries/Trackback.php b/system/libraries/Trackback.php
index a604c0b..a279144 100644
--- a/system/libraries/Trackback.php
+++ b/system/libraries/Trackback.php
@@ -356,7 +356,7 @@
 	{	
 		$tb_id = "";
 		
-		if (strstr($url, '?'))
+		if (strpos($url, '?') !== FALSE)
 		{
 			$tb_array = explode('/', $url);
 			$tb_end   = $tb_array[count($tb_array)-1];