correction for sorting in tables

the check for -1 give a wrong answer, we need to check for false.

Author: sirnone

adm_program/system/classes/htmltable.php

@@ -160,7 +160,7 @@ public function addRowByArray($arrayColumnValues, $id = null, $arrAttributes = n
         }
 
         // if body area wasn't defined until now then do it
-        if($this->tbody == -1)
+        if($this->tbody == false)
         {
             $this->addTableBody();
         }