XSB Src (SVN)-old

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.

All changes for answer-completion. (Redoes somethat got lost in the
sourceforge media crash.)

Add new tests for answer_completion, and
update right answers for old tests, now that answer completing is being done.

Added missing CTXTc tokens to lines 3287, 3288 and 3307 and striped trailing whitespace.

added MD5 to sha1