ShortLinks files Download Resume Support

Hi,
can you enable download resume support for the shorter internal links of owncloud ?
as for owncloud download links im getting resume support while downloading huge files.

```
via SetEnv MOD_X_SENDFILE_ENABLED 1
XSendFile On
XSendFilePath /var/www
```

This works fine with owncloud but with REMOTE-HOST index.php i cant get resume support of shrink download links.

Also
Feature request !
when we enabled link shortner and while getting short link from owncloud (by sharing), their must be 2 links provided one is shrinked one and other will be original owncloud download link.

Thanks for the lovely App.

Start at the REMOTE-HOST index.php path and reproduce a large-file download using the provided XSendFile settings, comparing the shortened link with the original ownCloud download link. Determine the expected behavior for resumed downloads and whether sharing should expose both URLs; done means both requested behaviors are specified and verified.

Written by the indexing model from the issue text.