Weak dictionaries and optimized variables

[Raphael Collet]

Christian,

> Whenever you do things also clean things.

I just figured out how to make it.  But it's not straightforward.

  // something like this for cell exchange
  am.prepareCall(BI_Unify, RefsArray::make(old,OZ_in(1)));
  return BI_REPLACEBICALL;


raph