mixin Efl.Access.Object inherits from abstract Efl.Object. So it is
regarded as class in some languages and it causes multi class
inheritance which is not allowed in some languages. (e.g. C#)
To resolve above, mixin Efl.Access.Object is changed to interface and
class Efl.Access.Widget is newly introduced.
class Efl.Access.Widget works like mixin Efl.Access.Object.
Efl.Ui.Widget attaches Efl.Access.Widget as its composite object.
So if Efl.Access.Object's method is called with Efl.Ui.Widget, then the
attached composite object Efl.Access.Widget works instead of
To introduce class Efl.Access.Widget, mixin Efl.Access.Widget.Action is
renamed to Efl.Access.Widget_Action to resolve namespace conflict.