XSB Src (SVN)-old

Fixed an obscure bug where string gc collected the Prolog atom '<cyclic>' which meant that cyclic terms were not
always properly marked. The solution is to always to a string_find at the beginning of mark_cyclic, and not rely
on its being interned at initialization, as had been done previously.

Adjusted slightly so this will work with mt engine.

Added a couple of explicit casts to quiet the Linux compiler.

Minor changes to make these files compile in the MT engine.

Took out spirious rm's.

This file somehow got corrupted -- removed.

added:
has_library_dir/1
remove_lib_dir/1
removeall_lib_dir/1
These are now needed for the user to facilitate checks because of file standardization.
Also added push(...) to add_library_dir. This is like a(...) but doesn't retract the directory -- onyly asserts-a.

added remove_lib_dir/1

backed out the standardization change to load_dunc/2, which was incorrect.
The other standardization changes stay.

remove xwams before running the tests so that the tests would be clean.