[doc patch] describe test directives in internals manual

[Gerald Pfeifer]

On Wed, 19 Jan 2005, Janis Johnson wrote:
> Thanks for your review, Gerald.  New proposed text follows each of your
> comments.  It was difficult explaining some of these directives, but I'm
> willing to try again if some of them still aren't clear.

Thanks!  I appreciate that it is in fact much harder to write this kind
of documentation than it is to review it, and the updates look great.

Gerald