XSB Src (SVN)-old

Changes for get_memory_size

Adding new file

Made temp tabled predicate to be opaque, to avoid issues with
incremental tabling. This breaks nothing in the testsuite.
(Teri should confirm it's the right fix.)

Minor changes in ac_tests (for easier benching.)
Minor change in delay_var, not to precall with cross-product, that I noticed
when tracing. Change mainly for clarity.

Changed way that answer-completion knows it's done: now uses simplification
flag set by completion to know that another iteration will give the same
result.

1. Added flag that indicates if simplification was done during completion.
It is used in answer_completion to avoid an extra iteration.
2. Improved (I think) building of delay lists (for get_residual), to be
slightly more resilient to heap movement in GC.

Eliminated several wasted cells on the heap (i.e., hreg was over-incremented.)

Changed way to determine whether a goal needs answer-completion. Now
it needs answer completion if it is in an SCC for which simplification
is done (and it's not early-completed.)

Minor changes in answer-completion: use force_truth_value(...,false)
instead of delete_return. It's more direct and should be slightly
more efficient. Use trie_get_return directly to avoid collecting all
answers just to see if there's one.

Changes for answer_completion.
Added predicate answer_completion/2 in tables.P that is called from
c (usually) and does answer completion.