This removes Efl.Pack_Named which had a terrible name,
removes Elm.Container which should have been renamed
Efl.Ui.Container anyway, and introduces an interface
Efl.Container instead.
The hierarchy tree is now changed as objects don't inherit
from Efl.Container (it's an interface, not a regular class)
but only implement it. Obviously it is very easy to
reintroduce an Efl.Ui.Container parent class if we need it,
but I guess it should have some actual logic. It's basically
part of what Elm.Widget already does.
Some function names have been modified to look better in C
with the efl_content prefix.
@feature
This reuses the Evas.Box code, since we are still using the
box internally. The flow layout function is far from perfect
(it works well only with items of same height).
This shows how to use specific layouts provided by EFL.
Jean-Philippe Andre
Amitesh Singh
Cedric BAIL