Description:
------------
ZipArchive::addFile does not work as expected when using windows directory 
separators (/).

Backslashes in string $filename are not converted into folders.





Test script:
---------------
$zip = new ZipArchive();

if ($zip->open() === true) {

	// gives a file named "dir/somefile.txt"
	$zip->addFile("dir".DIRECTORY_SEPARATOR."somefile.txt");

	// works properly
	$zip->addFile("dir/somefile.txt");
}

$zip->close();