edje: refactor edje color class API

Authored by conr2d on Jun 27 2016, 6:31 PM.


edje: refactor edje color class API

refactor setter and getter of edje color class and
move edje_color_class_set/get() into Edje.Object as class functions

Reviewers: cedric, jpeg

Reviewed By: jpeg

Subscribers: kimcinoo

Differential Revision: https://phab.enlightenment.org/D4109

Note by jpeg:
The EO APIs introduced here will be revisited in upcoming patches,
in particular:

  1. avoid non-premultiplied colors
  2. move to a common color class interface