Add empty line before alternative schemes, if needed

[sprain]

Fixes #142
See #142 (comment)

Fixes a situation where an additional empty line needs to be added if there is no billInformation but there are alternativeSchemes.

[demianh]

I can confirm this solves my problem from #142 (comment)

[demianh]

The validator shows a warning (not an error!) for the generated QR code:

(0048) - Element must only be deliverd if the element ist not empty. Exception: If subsequent elements are provided.

But i guess, that is a problem of the validator, that it can't handle the Exception.

Full validator output: Protocol.txt

[sprain]

Thanks for testing!

I am pretty sure that the validator is currently broken. I am in touch with SIX. See #241.

I will give them a few more days to get back to me again. Maybe we can then merge this with successfully validated qr codes.

Update: The most urgent validator issues seem to be fixed. The warning IMO is still a bug in the validator and I will let them know about it again. See screenshots validator vs. documentation.

[sprain]

Ok, SIX replied. This state of things is the best they can do in the validator. The warning will always be shown, even if the exception applies.