XSB Src (SVN)-old

(Please help me with a better name).
The various options for this predicate are explained, while the various incarnations of
load_dyn and load_dync are explained in terms of option choice for load_dyn_gen
(again, better name?). Even though load_dyn_gen (name?) is implemented just a fancy switch
to load_dyn(c) I think the explanation is now simpler and clearer.

As part of the manual revision I updated the discussion of static vs. dynamic code
in the System chapter, and added a discussion of canonical syntax in the Syntax chapter.