* Very old macros from the time Godot was created.
* Limited arguments to 5 (then later changed to 8) in many places.
* They were replaced by C++11 Variadic Templates.
* Renamed methods that take argument pointers to have a "p" suffix. This was used in some places and not in others, so made it standard.
* Also added a dereference check for Variant*. Helped catch a couple of bugs.
Now uses two interfaces so it can be overridden in the future, and
core no longer depends on Node.
The interfaces are implements in scene/multiplayer.
Replaces root_node with root_path.
Remove all Node references from MultiplayerAPI.
