[development] How do I send a file to the user?

[Ernst Plüss]

Having a closer look at
http://api.drupal.org/api/5/function/_locale_export_po showed gave me
the solution.

A die(); after sending out headers and excel data did the job. I don't
know exactly why this is needed, my guess is that if it's missing
somehow the next time a header is sent php thinks it belongs to the
same response and complains because already non header data has been
sent.

Thanks a lot for your assistance!
Ernst