* When called with a single argument to get a value, it allow to omit
the minus prefix.
* It can be called with keyword arguments to set attributes.
* w.wm_attributes(return_python_dict=True) returns a dict instead of
a tuple (it will be the default in future).
* Setting wantobjects to 0 no longer affects the result.
* Move Lib/tkinter/test/test_tkinter/ to Lib/test/test_tkinter/.
* Move Lib/tkinter/test/test_ttk/ to Lib/test/test_ttk/.
* Add Lib/test/test_ttk/__init__.py based on test_ttk_guionly.py.
* Add Lib/test/test_tkinter/__init__.py
* Remove old Lib/test/test_tk.py.
* Remove old Lib/test/test_ttk_guionly.py.
* Add __main__ sub-modules.
* Update imports and update references to rename files.
Serhiy Storchaka
Alex Waygood
Victor Stinner