The interface efl_part_get should not be directly called from C, but the efl_part
wrapper should. It rely on efl_noref to properly destroy the object. Binding can
control the lifecycle of the reference the way they want by either calling the
wrapper or efl_part_get directly. It also means that the ugly ___efl_auto_unref_set
doesn't need to be exposed outside of EFL anymore.
Differential Revision: https://phab.enlightenment.org/D6098
This prevents generation of del().
I also removed constructor, finalize and destructor as I believe this
requires special work with eo_inherit (where did this work go??).
It's VERY hacky, but works as expected: no leak, no extra unref. This is
a lucky case of simply overriding efl_part() implementation in C++,
without having to modify the declaration.