XSB Src (SVN)-old

Added get_sdg_subgoal_info/1 and print_sdg_subgoal_info/0, both useful for large SDGs.

Forgot to add this before.

Changes to allow WCS semantics for unknown predicates along with enabling a user_hook for them.

Changes to get the MT engine compiling again.

Move this test here, as tripwires aren't supported in the MT engine.

Update to make MT engine run more of the test suite.

Documentation of undefined and hook options when loading an unknown predicate.

Fixed multithreaded calls to throw_permission_error that I just added.
Thanks, Barry.

Forgot to include this in previous commit.

Added some error checking for read/write errors to throw more
instructive permission errors in case of errors. Much more to be
done, but this is a (small) start. This is becoming more important as
XSB, Inc. runs large, long-running programs over sometimes flakey
networks, and we need to be told if/when the network goes down.