Optimize closing of file handle in StreamReader class about fpdi

[MaximilianKresse]

Following test will fail at the moment:

<?php

use setasign\Fpdi\Fpdi;

$pdf = new Fpdi();

$originalFile = '_files/pdfs/Boombastic-Box.pdf';
$file = 'file1.pdf';
copy($originalFile, $file);

$pdf->setSourceFile($file);
unset($pdf);

$newFile = 'file2.pdf';
rename($file, $newFile);

This could be fixed by using gc_collect_cycles after unset($pdf). The real issue here is the PdfParser class. It creates and referencing to an instance of CrossReference while the CrossReference instance have a reference to the PdfParser both classes have references to each other. This will only be resolved on the next garbage collect cycle.

To resolve this I implemented a cleanUp method for the PdfParser class which is called in the PdfReader destructor.