XSB Src (SVN)-old

Defining undefined.

Making undefined standard.

adding definition of undefined/0.

fixing stest.sh

Added (some) constraint tests for call subsumption.

taking catch1 out -- now that we have attributed variables in answers
for tables with call_subsumption.

Changed . to ..

Marking (in mark_root) tries to check whether structure-tagged pointer
indeed points to a PSC pointer. That test however would let pass non-reference
values; clearly strange. This situation just arose (in the compiler), so I added that check.
So it may be that this is necessary, but just never arose before, or it could
be that there is another bug in constructing structure pointers that this has
uncovered.
I've generated a warning if this case arises. This may just be kicking the
problem down the road.

Uncommented out the definition of undefined.

Added definition of undefined. (Unclear, to me, why it wasn't here.)