Weekend work. The main points:

Weekend work.  The main points:

* Type::getCardinality() returns the cardinality for for all types.
  Theories give a cardinality in the their kinds file.  For
  cardinalities that depend on a type argument, a "cardinality
  computer" function is named in the kinds file, which takes a
  TypeNode and returns its cardinality.

* There's a bitmap for the set of "active theories" in the
  TheoryEngine.  Theories become "active" when a term that is owned by
  them, or whose type is owned by them, is pre-registered (run CVC4
  with --verbose to see theory activation).  Non-active theories don't
  get any calls for check() or propagate() or anything, and if we're
  running in single-theory mode, the shared term manager doesn't have
  to get involved.  This is really important for get() performance
  (which can only skimp on walking the entire sub-DAG only if the
  theory doesn't require it AND the shared term manager doesn't
  require it).

* TheoryEngine now does not call presolve(), registerTerm(),
  notifyRestart(), etc., on a Theory if that theory doesn't declare
  that property in its kinds file.  To avoid coding errors,
  mktheorytraits greps the theory header and gives warnings if:
  + the theory appears to declare one of the functions (check,
    propagate, etc.) that isn't listed among its kinds file properties
    (but probably should be)
  + the theory appears NOT to declare one of the functions listed in
    its kinds file properties

* some bounded token stream work