Changes to:

* Fix bug printing method types (oops when converting previous code)
* Move some of the code from Constant::getStrValue implementations here.
  This allows us to do a MUCH MUCH better job printing out complex constant
  values (think an array of structure pointers), because we print symbolic
  type names instead of structural.  The assistance when debugging is immense

Eventually, Constant::getStrValue should be removed (it existed before because
the asmwriter file was not in VMCore), and everyone should go through the
asmwriter that want's equivalent functionality.

llvm-svn: 2268