Closes SF patch #103123.

funcobject.h:

    PyFunctionObject: add the func_dict slot.

funcobject.c:

    PyFunction_New(): Initialize the func_dict slot to NULL.

    func_getattr(): Rename to func_getattro() and change the
    signature.  It's more efficient to use attro methods and dig the C
    string out than it is to re-convert a C string to a PyString.

    Also, add support for getting the __dict__ (a.k.a. func_dict)
    attribute, and for getting an arbitrary function attribute.

    func_setattr(): Rename to func_setattro() and change the signature
    for the same reason.  Also add support for setting __dict__
    (a.k.a. func_dict) and any arbitrary function attribute.

    func_dealloc(): Be sure to DECREF the func_dict slot.

    func_traverse(): Be sure to traverse func_dict too.

    PyFunction_Type: make the necessary func_?etattro() changes.

classobject.c:

    instancemethod_memberlist: Add __dict__

    instancemethod_setattro(): New method to set arbitrary attributes
    on methods (really the underlying im_func).  Raise TypeError when
    the instance is bound or when you're trying to set one of the
    reserved im_* attributes.

    instancemethod_getattr(): Renamed to instancemethod_getattro()
    since that's what it really is.  Also, added support fo getting
    arbitrary attributes through the im_func.

    PyMethod_Type: Do the ?etattr{,o} dance.