Store md5 computation if missing to speed up future queries

            if (empty($path)) {

                $path = $this->filePath;

            }

            // Pretty much faster if it is available

            if (file_exists($path . ".md5sum")) {

                $tmp = explode("  ", file_get_contents($path . '.md5sum'));

                $ret = $tmp[0];

            } elseif ($this->commandExists('md5sum')) {

                $tmp = explode("  ", exec('md5sum ' . $path));

                exec('md5sum ' . $path. ' > '.$path.'.md5sum');

                $tmp = explode("  ", file_get_contents($path . '.md5sum'));

                $ret = $tmp[0];

            } else {

                $ret = md5_file($path);

            return $ret;

        }

        /* Getters */

        /**