PyAtkObject: Fix internal object instantiation and reference counting

From: Daniel Drake <d.drake@mmm.com>

The code is currently using PyObject_New to instantiate objects from C, but
this does not properly initialize the objects.

References:

http://mail.python.org/pipermail/python-dev/2002-April/022877.html
http://mail.python.org/pipermail/python-list/2005-April/318746.html

Right now, _atkobject_get_parent() creates a mostly-uninitialized object.
Later on, when _atkobject_dealloc is called, self->dict is some garbage pointer
which we run Py_DECREF on --> crash

Also, I noticed that _atkobject_dealloc decreases the reference count on
the ATK object, so I also fixed up _atkobject_get_parent to increment the
reference count.

Index: papi-0.0.2/src/papi_atkobject.c
===================================================================
--- papi-0.0.2.orig/src/papi_atkobject.c
+++ papi-0.0.2/src/papi_atkobject.c
@@ -220,14 +220,7 @@ _atkobject_new (PyTypeObject *type, PyOb
     PyAtkObject *self;
 
     debug ("_atkobject_new\n");
-
-    self = (PyAtkObject *) type->tp_alloc (type, 0);
-    self->dict = NULL;
-    self->prop_handlers = NULL;
-    self->weakrefs = NULL;
-    self->obj = NULL;
-
-    return (PyObject *) self;
+    return PyType_GenericNew (type, args, kwds);
 }
 
 /**
@@ -398,8 +391,9 @@ _atkobject_get_parent (PyAtkObject *self
     val = atk_object_get_parent (ATKOBJECT (self));
     if (val)
     {
-        PyAtkObject *obj = PyObject_New (PyAtkObject, &PyAtkObject_Type);
-        obj->obj = val;
+        PyAtkObject *obj = PyAtkObject_Type.tp_new (&PyAtkObject_Type, NULL,
+                                                    NULL);
+        obj->obj = g_object_ref (val);
         return (PyObject *) obj;
     }
     Py_RETURN_NONE;
@@ -481,7 +475,7 @@ _atkobject_ref_accessible_child (PyAtkOb
         return NULL;
 
     val = atk_object_ref_accessible_child (ATKOBJECT (self), i);
-    obj = PyObject_New (PyAtkObject, &PyAtkObject_Type);
+    obj = PyAtkObject_Type.tp_new (&PyAtkObject_Type, NULL, NULL);
     obj->obj = val;
     return (PyObject *) obj;
 }