Add method visibility declarations and optimize display_errors() method in Image_lib, Trackback and Upload libraries
diff --git a/system/libraries/Upload.php b/system/libraries/Upload.php
index 66e91c5..ab97d1a 100644
--- a/system/libraries/Upload.php
+++ b/system/libraries/Upload.php
@@ -934,13 +934,7 @@
 	 */
 	public function display_errors($open = '<p>', $close = '</p>')
 	{
-		$str = '';
-		foreach ($this->error_msg as $val)
-		{
-			$str .= $open.$val.$close;
-		}
-
-		return $str;
+		return (count($this->error_msg) > 0) ? $open . implode($close . $open, $this->error_msg) . $close : '';
 	}
 
 	// --------------------------------------------------------------------
@@ -1086,4 +1080,4 @@
 // END Upload Class
 
 /* End of file Upload.php */
-/* Location: ./system/libraries/Upload.php */
\ No newline at end of file
+/* Location: ./system/libraries/Upload.php */