Add new files atk/atkgobjectaccessible.c atk/atkgobjectaccessible.h

docs/tmpl/atkgobjectaccessible.sgml

* atk/Makefile.am atk/atk.h:
Add references to new files

* atk/atkobject.c atk/atkobject.h
docs/tmpl/atkobject.sgml:
Add new function atk_object_initialize

* atk/atkobjectfactory.c atk/atkobjectfactory.h
docs/tmpl/atkobjectfactory.sgml:
Add new function atk_object_factory_get_accessible_type

* docs/atk-sections.txt:
Add new functions.
Add functions in atk-unused.txt