Andy and John: (if possible) automatically turn expressions with array
sub-expressions into iteration over the array(s)

Andy: Change primNull to another name (null is not primitive).

Andy: Decide if we should change vm::error to em in application.cc

Andy: Add info to vm to aid debugging.  (Locations are a start, but we can add
variable names, type info, stack traces).

John or Andy: Add unit test for AddOps.

Andy: Fix: void f(int x=blah);

Andy: Clean up processData and preRun
