XSB Src (SVN)-old

Change way terms are copied in creating incr lists of changed terms,
so that the heap is in a valid state if (when) glstack_realloc and
gc_heap might be called. Avoids segfault in gc_heap.

Changes to error_xsb.[ch] to turn current xsb_throw to xsb_throw_internal, and then re-introduce xsb_throw(). This allows xsb_throw to be used more easily
by foreign C functions and will hopefully solve Roberto Bagnara's problem.

Other changes fixed some typos in error messages.

Saikat eliminated many leaks

Modified consult so that it will consult files with extensions other than
the standard ones that XSB recognizes. (Stimulated by aleph, an ILP program
that wants to consult a file with a .b extension.)
Also fixed to allow these files to be consulted on windows, which doesn't
have a file link operation that is used. It now uses filecopy for windows.
Not great, but better than crashing...

Updated memory management in hashtable (which manages hashing for incremental
table maintenance.) It now uses XSB mem_alloc and friends, and there is a new
space type of INCR_TABLE_SPACE. It is included in SLG Table space in statistics
and is also broken out (if nonzero).
And doing that showed a huge amount of unused space due to many large hashtables
when there's only one edge. So I changed the minimum size of initial hashtables
(they are automatically expanded if necessary.) [It reduced incr space usage in
my DSS example from about 340M to 8M... much!! better.]

A bug fix in propagation rule's compilation

Take out earlier attempt to ensure that string gc doesn't access uninitialized
portions of findall chunks. The mem_calloc makes this code redundant (and it didn't
work anyway.)

Initialized chunks by using mem_calloc (just to see if it shuts valgrind up...)

Changes to get rid of uninitialized memory as reported by valgrind.

1) Initialized IGRhead and deadlock_brk_leader
2) Ensured that tries always use private structure manager
3) initialized num_heap_term_vars to be 0 at each pass through answer_return

The last fixes an obscure memory error in the sequential engine, as well.

Modified test to get rid of a race condition.