They work exactly the same as current checkbox-decorated items, but in order to preserve compatibility, separate methods are used, like `add_radio_check_item()`. The other option would have been to add a new parameter at the end of `add_check_item()` and the like, but that would have forced callers to provide the defaults manually.
`is_item_checkable()`, `is_item_checked()` and `set_item_checked()` are used regardless the item is set to look as check box or radio button.
Keeping check in the name adds an additional clue about these facts.
Closes#13055.
This partially reverts commits e79456519d
and 2d07fe2920, which introduced API changes
needing more in-depth review at this stage.
Kept the removal of "get_position" binding, redundant with
"get_current_animation_position". Kept docs changes where applicable.
Also removed the obsolete "stop_all" method which does the same as "stop".
Fixes#14602.
