feature: BaseShape.hover_action

[urbov]

It seems that everything was prepared but hover_action seems to be missing. I only found click_action to be available.

If you point me into the right directions, I can add them for you.

[urbov]

It seems that adding the function below to base.py is all I need.

    @lazyproperty
    def hover_action(self):
        """
        An |ActionSetting| instance providing access to the mouse hover
        behaviors defined on this shape. An |ActionSetting| object is always
        returned, even when no hover behavior is defined on the shape.
        """
        cNvPr = self._element._nvXxPr.cNvPr
        return ActionSetting(cNvPr, self, True)