XSB Src (SVN)-old

Updates for interning ground structured terms; adding new .c and .h file.
And other things I don't exactly understand. These files all work for me,
so I hope it doesn't break anyone else's system.

Added comment (after end_of_file.) that describes a bug that I don't
have time to track down now. For future work...

Many changes, motivated by adding intial code to support interning
of ground structured terms. This code is not ready for prime time,
but seems not to break anything if it is not used.
Also a few minor bug fixes noticed along the way.

Many updates: almost all due to initial coding in preparation for
supporting the interning of ground structured terms. At this point
none of this code is "active". The user can explicitly intern ground
structures, but they are not fully debugged. In particular, GC doesn't
work with them.
Other minor updates discovered along the way.

New files to implement interning of ground structured terms.
Basic functions.

Update due to new error message given by XSB

Update to make more files.

On windows, differentiate between 32 and 64-bit versions on initialization.

For windows, differentiate between 32 and 64-bit versions on initialization.

Fixed bug in answer subsumption. Problem was that '/'/2 was used in
generated code, and so in a module was treated as a local symbol.
This then conflictd with later uses in the compiler. Made it global,
and also for var/0 as well, to be safe.