XSB Src (SVN)-old

New bit in subgoal frame to flag answer_completed.
New builtin to set and get it from prolog.
Various points in C to set/reset it (esp. in simplification).
Calls in check_complete and tabletry to Prolog's answer_completion/2 pred.
Check and fail if delay would cause immediate direct recursion through
a ground subgoal in residual program.
Fixes a bug in simplification that didn't reset subg_answers right.
New bit added to trie_get_return so Prolog can get delay list returned.
And probably a few more minor things.