Removed inadequate "die" statement while rendering

When called in a context where other code is expected to be executed after rendering (i. e. in a MVC app where some shutdown stuff is to be done after preparing the response), a "die" within third party code leads to unexpected behaviour. I would suggest to remove it and leave it up to the caller when to exit.

Use case:
<?php
ob_start();
$myQrCode->render();
$binaryImageData = ob_get_clean();
// Do some other stuff here ...