strings. This is needed because cPickle (still) uses
	  a restricted eval to parse non-binary string pickles.
	  This change is needed to prevent pickles like::

	    "S'hello world'*2000000\012p0\012."

	  from hosing an application.

	- User-defined types can now support unpickling without
	  executing a constructor.

	  The second value returned from '__reduce__' can now be None,
          rather than an argument tuple.  On unpickling, if the
	  second value returned from '__reduce__' during pickling was
	  None, then rather than calling the first value returned from
          '__reduce__', directly, the '__basicnew__' method of the
          first value returned from '__reduce__' is called without
	  arguments.

Added rexec support.

Added new machinery to avoid calling instance constructors if
no __getinitargs__.

Later we should allow multiple values for the same name.