Rest of patch that should not be cherry picked into 3.5.2 final.

Fix code and tests that fail with this restriction.
Fix htests to not create a second and redundant root and mainloop.

load() and loads() functions and JSONEncoder and JSONDecoder class
constructors in the json module are now keyword-only.

I noticed that there is no test for this feature while doing
triaging work on pypa/pypi-legacy.

and selection_toggle() of ttk.TreeView now allow to pass multiple items as
multiple arguments instead of passing them as a tuple.  Deprecated
undocumented ability of calling the selection() method with arguments.

framework builds.

represented as a compination of known flags.

represented as a compination of known flags.

represented as a compination of known flags.

Patch contributed Марк Коренберг.

Patch contributed Марк Коренберг.

as group indices.  Based on patches by Jeroen Demeyer and Xiang Zhang.

an iterable of integers. Now only strings and byte-like objects are accepted.

an iterable of integers. Now only strings and byte-like objects are accepted.