Remove RES and REF typedefs in favor of spelled out Ref<>

These typedefs don't save much typing compared to the full `Ref<Resource>`
and `Ref<RefCounted>`, yet they sometimes introduce confusion among
new contributors.

editor/editor_data.cpp

@@ -82,7 +82,7 @@ void EditorSelectionHistory::add_object(ObjectID p_object, const String &p_prope
 	RefCounted *r = Object::cast_to<RefCounted>(obj);
 	_Object o;
 	if (r) {
-		o.ref = REF(r);
+		o.ref = Ref<RefCounted>(r);
 	}
 	o.object = p_object;
 	o.property = p_property;