TestGL Issues list (alpha release)

Attached is a preliminary issues list for TestGL. It incorporates all of 
the comments from minutes of our discussions in Boulder (even when I 
couldn't understand what these meant) plus additional feedback from 
Dimitris, Mark, and myself.

I modelled the format of the table on our SpecGL issues list, but 
tweaked it slightly (hopefully you'll see the value of the changes I've 
made).

Please review the issues, and send feedback. I'm particularly interested 
in clarifications of the questions embedded within the text (most of 
these are preceded '[PC]') but you should also feel free to respond to 
the comments from [MS] and [DD].

Of course, additional issues will also be welcomed.

Thanks...