- New Wired-in Id: getTag# :: a -> Int#
	for a data type, returns the tag of the constructor.
	for a function, returns a spurious number probably.
	dataToTag# is the name of the underlying primitive which
	pulls out the tag (its argument is assumed to be
	evaluated).

- Generate constructor tables for enumerated types, so we
  can do tagToEnum#.

- Remove hacks in CoreToStg for dataToTag#.