XSB Src (SVN)-old

Improved handling of variables in group-by arguments it lattice answer
subsumption. Not perfect, but better.

added the character_set(...) compiler_option.

Fixed fat-fingered typo...

Fixed bug in builtin file_set_character_set.

Add predicate: file_set_character_set/2 to take a stream indicator and a
character set identifier and set the charset for that stream as indicated.

Added option to file_function to set charset of open file (intended for
use with userout or userin).

Changed (partially) calls to stat to be calls to __stat64 on windows64
(with corresponding change to stat buffer) since stat seems to have
recently changed to fail on files with sizes > 2^31-1. Changed call
at open, where it bit us, but didn't change all stat calls. Got too
tricky, so can change those as we discover problems...

Several refinements.

Manual: fixed incorrect reference to Character Sets.
Windows: fixed xsb_configuration, which was missing build_date.

ignored *_new files (on git)
updated banners

Yet another bug in traverse_variant_answer_trie - those pesky hash
tables again. In this case the traversal was not properly pushing
information pertaining to hash tables onto the stack when the
traversal occurred via encountering a hash node during traversal
of the unseen nodes of the trie. Another case, where information was
pushed onto the stack when initialziing information from a segment of
choice points was in fact working properly (a prior bug).

This fix solves a CMU-SEI problem, but I need to look at it with fresh
eyes to see if its general or not.