XSB Src (SVN)-old

Backed out changes from 9226 which incorrectly changed the types of some opcodes etc. in a couple of functions.

Added minor code to compiler to support the form:
p(X,---) :- X = f(a,b), ...
to use the f(a,b) to index on the first argument. (Works for any argument.)
Finally can get indexing *and* avoid reconstructing the term on the heap.
This is not applied to tabled predicates (since it causes a segfault.)
I should try to figure out why. I suspect there might be a program
transformation that it's intefering with.

allow hooks to have non-atomic types

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.