Weak Pointers & Weak Tables done !!!

[Mark S. Miller <mark>]

We now have working refCount style garbage collection, object-level
backfollow, strong & weak pointers, notification that something you
are referring to is about to go away, and weak tables.  Garbage
collection of Orgls & Berts coming up, with a new improved backfollow
following shortly thereafter.

P.S.  Garbage collection bugs sure get subtle & wierd.