Convert the weakref test suite to PyUNIT, and add tests that exercise weak

references on function objects and both bound and unbound methods.

Lib/test/output/test_weakref

 test_weakref
-Basic Weak References
--- Liveness and referent identity
--- Reference objects with callbacks
--- Proxy objects with callbacks
--- Re-use of weak reference objects
-     reference objects
-     proxy objects
-clearing ref 2
-clearing ref 1
-clearing ref 2
-clearing ref 1
-
-Weak Valued Dictionaries
-objects are stored in weak dict
-weak dict test complete
-
-Weak Keyed Dictionaries
-objects are stored in weak dict
-weak key dict test complete
-
-Non-callable Proxy References
-XXX -- tests not written!
-
-Callable Proxy References