Filesystem driver , score calculation -- fix proposal

[ThierryNapspirit]

Using 'filesystem' driver , score calculation does not work.

I fixed this bug on "TNTIndexer.php" , function "readDocumentsFromFileSystem"

// "total_documents" is already defined... so an INSERT won't work... use UPDATE (or the ready to use function "updateInfoTable".
// $this->index->exec("INSERT INTO info ( 'key', 'value') values ( 'total_documents', $counter)");
$this->updateInfoTable('total_documents', $counter);

I also changed the way search is returned using the 'filesystem' driver.
File "TNTSearch", function "search".

        if ($this->isFileSystemIndex()) {
            return [
                'ids'            => array_values($this->filesystemMapIdsToPaths($docs)->toArray()),
                'hits'           => $totalHits,
                'docScores'      => $docScores,
                'execution_time' => round($stopTimer - $startTimer, 7) * 1000 ." ms"
            ];
        }

Great library.
Many thanks.

Thierry.