Revert "Eo: Remove eo_del() and make eo_unref() the replacement."

This reverts commit 546ff7bbba788ec834c5608361c0834853f2d5d7.

It seems that eo_del() is useful and removing it was creating bugs.
The issue is that the way we defined parents in eo, both the parent and
the programmer share a reference to the object. When we eo_unref() that
reference as the programmer, eo has no way to know it's this specific
reference we are freeing, and not a general one, so in some
circumstances, for example:
eo_ref(child);
eo_unref(child); // trying to delete here
eo_unref(container); // container is deleted here
eo_unref(child); // child already has 0 refs before this point.

We would have an issue with references and objects being freed too soon
and in general, issue with the references.

Having eo_del() solves that, because this one explicitly unparents if
there is a parent, meaning the reference ownership is explicitly taken
by the programmer.

eo_del() is essentially a convenience function around "check if has
parent, and if so unparent, otherwise, unref". Which should be used when
you want to delete an object although it has a parent, and is equivalent
to eo_unref() when it doesn't have one.

unsorted/ecore/ecore_audio_playback.c

@@ -201,7 +201,7 @@ static Eina_Bool _play_finished(void *data EINA_UNUSED, const Eo_Event *event)
 
   inputs = eina_list_remove(inputs, event->object);
   ret = ecore_audio_obj_out_input_detach(out, event->object);
-  eo_unref(event->object);
+  eo_del(event->object);
 
   if (!ret)
     printf("Could not detach input %s\n", name);

unsorted/ecore/ecore_audio_to_ogg.c

@@ -24,8 +24,8 @@ static Eina_Bool _play_finished(void *data EINA_UNUSED, const Eo_Event *event)
   printf("Done: %s\n", name);
 
   ecore_audio_obj_in_output_get(event->object, &out);
-  eo_unref(event->object);
-  eo_unref(out);
+  eo_del(event->object);
+  eo_del(out);
 
   ecore_main_loop_quit();
 
@@ -54,7 +54,7 @@ main(int argc, char *argv[])
    ret = ecore_audio_obj_source_set(in, argv[1]);
    if (!ret) {
      printf("Could not set %s as input\n", argv[1]);
-     eo_unref(in);
+     eo_del(in);
      return 1;
    }
 
@@ -64,16 +64,16 @@ main(int argc, char *argv[])
    ret = ecore_audio_obj_source_set(out, argv[2]);
    if (!ret) {
      printf("Could not set %s as output\n", argv[2]);
-     eo_unref(in);
-     eo_unref(out);
+     eo_del(in);
+     eo_del(out);
      return 1;
    }
 
    ret = ecore_audio_obj_out_input_attach(out, in);
    if (!ret) {
      printf("Could not attach input\n");
-     eo_unref(out);
-     eo_unref(in);
+     eo_del(out);
+     eo_del(in);
      return 1;
    }
 

unsorted/elementary/performance/graphical.c

@@ -289,7 +289,7 @@ _change_scene_setup()
      {
         evas_canvas3d_node_member_del(globalGraphical.root_node, node);
         globalGraphical.list_nodes = eina_list_remove(globalGraphical.list_nodes, node);
-        /*eo_unref(node);Unless evas_canvas3d_destructors work properly*/
+        /*eo_del(node);Unless evas_canvas3d_destructors work properly*/
      }
    eina_list_free(globalGraphical.list_nodes);
    eina_list_free(l);
@@ -298,7 +298,7 @@ _change_scene_setup()
    EINA_LIST_FOREACH (globalGraphical.list_meshes, l, m)
      {
         globalGraphical.list_meshes = eina_list_remove(globalGraphical.list_meshes, m);
-        /*eo_unref(m); Unless evas_canvas3d_destructors work properly*/
+        /*eo_del(m); Unless evas_canvas3d_destructors work properly*/
      }
    eina_list_free(globalGraphical.list_meshes);
    eina_list_free(l);