XSB Src (SVN)-old

In some Flora programs with defeasible reasoning, a
mysterious "null node" warning had been printed out. It turned
out that this was being emitted by find_answers_for_subgoal(),
which is used in cascading abolishes. The problem arose for
deleting calls that had empty answer tries, where a stack was
checked, a null node immediately found, and the routine exited.
In this case, it was harmless, but I added a check to get rid of
the warning in this case, and made the warning itself more
descriptive.

Fixed typo in tables.c

In tst_aux.h fixed so that tables created by call subsumption allow
attributed variable constraints in their answers (including in delay
elements). Calls in call subsumption still cannot include attributed
variables -- I need to understand more about Bao's algorithm before
I'll be ready to add them there. But having them in answers takes us
at least part of the way.

Changes were mostly for documentation and code refactoring.

However, also fixed a latent bug in simplification where
was_simplifiable was not properly checking negative delay elements
corresponding to subsumed subgoal frames. This led to the possibility
of adding un-needed delay elements that might not have been simplified
away. Surprisingly enough, however, none of the tests in the test
suite checked for this.

Adding a new test for copying attributed variables into delay elements
/ lists. I hadn't thought this worked, but apparently it does !

Also, I'm adding a very simple test for incremental evaluation -- more
cases need to be added here, but at least this is a start.

adding dret_test.P to subsumptive tests.

Adding a new test for copying attributed variables into delay elements
/ lists. I hadn't thought this worked, but apparently it does !

Also, I'm adding a very simple test for incremental evaluation -- more
cases need to be added here, but at least this is a start.

Fine tuning for exclude tests (to run call subsumption tests under batched).

Updating a number of files so that delete_branch() will work with call
subsumption (it needs to know that it deallocates BTNs rather than
TSTNs). This fixed a latent bug in simplification and allows another
test to be run for call subsumption. It also provides a step towards
supporting answer subsumption on call subsumptive tables. There are
also some other documentationstyle changes.

Adding a new test for copying attributed variables into delay elements
/ lists. I hadn't thought this worked, but apparently it does !

Also, I'm adding a very simple test for incremental evaluation -- more
cases need to be added here, but at least this is a start.

Fixed so that batch test tests only neg_tests for subsumption. Still
need to fix delay_tests and wfs_tests to work under batched.

added a missing } to is_number_atom

Also, took out restrictions that predicates that use call subsumption
cannot delay.