Remaining problems in SWI-Prolog

* Still, we have to search for a solution to garbage collection
  while foreign code is active.

* Read/1 is buggy.  Operator resolution still does not solve all problems
  correctly.

  See:

  	?- op(900, fy, cd).
	
	cd :- cd ~.

  is read as cd (:- cd ~).

* Bagof/setof have a bug as reported by Paul Broome <broome@BRL.MIL>:

  The symptons are that variable bindings in subgoals of bagof seem to
  be lost.  An example that illustrates the problem is the following:

  | ?- bagof(Z,(X=Z),L).
 
  L = [G206]
  X = G148
  Z = G149 ;
 
  The variables G206 and G148 are the same but this fact is lost.
