Easy export filter testing

[Caolán McNamara]

On Mon, 2013-12-09 at 09:59 +0100, Miklos Vajna wrote:
> I guess it would help a lot if test::FiltersTest could do export
> testing as well, like: I put a bunch of documents in a directory,
> specify what export filter to use, and it would fail if some of them
> fail. (Probably the pass/fail separation is not that meaningful for
> export, as AFAIK export always succeeds.)
> 
> Caolán, do I remember correctly that FiltersTest is your baby? Any
> objections?

I have no objections re export twiddling. It was the import and the
ability to shovel a load of documents into the "indeterminate" dirs and
just run make that I was interested in.