Added switch to error log

This makes it possible to disable the error log and set the path to the
error log file. Ideally this would be implemented with a logging
interface to allow to use third party loggers.

src/class.seostats.config.php

@@ -39,4 +39,7 @@
         'member-881a55bcfb');
     define('SEOMOZ_SECRET_KEY',
         '7145d56a1279285be92e6e4875bba8ee');
+
+    define('ERR_LOG_ENABLED', true);
+    define('ERR_LOG_PATH', 'errlog.txt');
 ?>

src/class.seostats.php

@@ -128,13 +128,19 @@ public function __construct($url)
         }
     }
 
+    /**
+     * Logs an error to the error log file
+     * 
+     * @param  String $errtxt The error message to log
+     */
     function errlogtxt($errtxt)
     {
-        $fp = fopen('errlog.txt','a+'); //ouvrir le fichier
-        $newerr = date('Y-m-d\TH:i:sP') .' : ' . $errtxt."\r\n"; //creation du texte de l'erreur
-        fwrite($fp,$newerr); //edition du fichier texte
-        fclose($fp); //fermeture du fichier texte
-        echo $newerr;
+        if (ERR_LOG_ENABLED) {
+            $fp = fopen(ERR_LOG_PATH,'a+'); 
+            $newerr = date('Y-m-d\TH:i:sP') .' : ' . $errtxt."\r\n";
+            fwrite($fp,$newerr); 
+            fclose($fp);
+        }
     }
 
     /**