Evas Canvas: Remove focused_objects property.

Evas Canvas: Remove focused_objects property.

Summary:
This property is not needed and it will only increase the API size.
One can simple achieve the same behaviour by simple doing:

//C code...

Eina_List *l;
Evas_Device *dev;

devices = evas_device_list(evas, NULL);

EINA_LIST_FOREACH(devices, l, dev)
{
   Evas_Object *obj;

   if (evas_device_class_get(dev) != EVAS_DEVICE_CLASS_SEAT)
      continue;
   obj = evas_canvas_seat_focus_get(dev);
   //Do something with the focused object.....
}
//More C code...

Reviewers: bdilly, barbieri, conr2d, jpeg

Reviewed By: jpeg

Subscribers: cedric, jpeg

Differential Revision: https://phab.enlightenment.org/D4547