Magic macros in the destination URL don't work with 3rd party click tracking (ct0)

If the ct0 parameter is supplied (i.e. when 3rd party click tracking is enabled), any magic macro present in the banner destination URL isn't replaced.

Comment from Erik:
> We've tested this "in the field" today and I can confirm that this change fixes the issue.
> 
> We thank our client EuroRelais (see: http://www.eurorelais.nl/ ) for funding the development and testing of this fix.