Bug#359059: lintian: Allow vendor/user specific checks

[Niels Thykier <niels@thykier.net>]

On 2012-09-17 13:49, Niels Thykier wrote:
>  * Where do contrib checks install their data files?
> 
>    A suggestion could be:
>      <root>/vendors/contrib/<X>/...
>    and have Lintian special case it.

Looking at the code needed to do this special casing, we might as well
just restore the <root>/data dir and include that in the end directly.

Contrib checks would then just put their data files in:
   <root>/data/contrib/X/...

As an added bonus, the "special casing" does not need any additional
testing because all the "standard" data files would be loaded from there
as well.  Yay!

~Niels