XSB Src (SVN)-old

Much new documentation.
Small small optimizations.
A few other changes.

Added write_canonical_lettervar/2, to be consistent with all other
write-like predicates, to handle open files *and* userout in first arg.

Made clause handle explicit module modifier of head.
Also a couple of cleanups (since term_new_mod preserves arguments.)

In pathname_xsb.c: path_sysop(standardize,path,out) now strips trailing \ in windows, making it consistent with Linux/Mac
In timer_xsb.h: fixed declaration (win32) to be consistent with the MSVC studio.

Took out spurious warning from predicate_property.

Test for incremental tabling problem that fixed in a prior commit, where callnode-> recomputable
was not properly resent on propagate_no_change.

Changes to fix a bug in tripwire version of maxans.

Added a new test for test...maxans.

Changes for
* table...maxan
* 'custom' option for tripwires
* Fix for coredump on undefined predicates involved in ?- queries in compiled files.

More for maxans + updated debugging messages for incremental tabling (commented out in tables.c)