Dropped end-to-end tests from haskell test runner (removed support for --plan
flag for ./dyna). These test are now part of python test runnner.

Minor refactoring/reorganization of interpreter and repl.
()
maintain a coarse dependency graph of head->evals and a map functor->rules (all
rules [not just BC rules] know their head's functor -- i.e. an overestimate of
what they "create"). These changes are nonfunction, but will facilitate
maintenance, retraction and all that.
anf file required.
Clean up agenda loop.
refactored code, resolved asymmetries between FC and BC (and within each) --
code now has fewer special cases and should have fixed a bunch of bugs we didn't
even know we had :-X

don't show BC items in changes.

(BC retraction has improved, but it's still not 100% correct thanks to stale
memos)