Get rid of the "with" part -- we don't think we need it after all.
Checking in some temp stuff.
Completely rewritten idempotent trace implementation.  Includes handler pools and freezing.  Deforested (Trace is no longer an ADT).
Completed non-scalable versions of support data structures (bags and counters)
Fix infuriating Redex grammar bug.
Redex sketching.  Don't know how to deal with E-Spawn-Handler yet.
Added commentary about representation.
Some work on E-Spawn-Handler and downset stuff.
Added coordination between freeze and put to ensure correct faulting behavior.
Added freezeLVAfter
Removed 'trace' from the name of the Idempotent implementation, since the datatype no longer exists.
Added example IVar implementation for LVarIdempotent.
E-Spawn-Handler perhaps closer to working.
E-Spawn-Handler and downset stuff working, I think!
Merge branch 'temp'