FIXED: Added meta-predicate declaration for expand_term/4 and
moved meta predicate declarations of public predicates to the
start of the file to support the development tools.
FIXED: Meta-call declarations wrt. expand_goal/4.
ADDED: Unify Goal in expand_goal/4, so we do not need to pass it
through the closure anymore.
Moved expnd_goal/4 into expand_goal/5
Pass variables through expand_term/5.
Remove Caller from expand_term processing
Fix expand_sentence to new stuff
Make replace_* calls use new interface
FIXED: Use library(prolog_source) for safe(r) reading of source terms.
Don't need this anymore
Comment a little
Allow not to bind the pattern to the term (not really used)
Got expand_term/5 to work again.  Need to do the others.
WIP: trying to get expand_goal/5 to work (doesn't)
Working t4 (needs cleaning)
Added a little comment
More comments
Working on comments
Commenting the rationale behind the term copying
Cleanup the code and clarify why it works.