Refactored Node3D rotation modes

* Made the Basis euler orders indexed via enum.
* Node3D has a new rotation_order property to choose Euler rotation order.
* Node3D has also a rotation_mode property to choose between Euler, Quaternion and Basis

Exposing these modes as well as the order makes Godot a lot friendlier for animators, which can choose the best way to interpolate rotations.
The new *Basis* mode makes the (exposed) transform property obsolete, so it was removed (can still be accessed by code of course).

scene/audio/audio_stream_player.cpp

@@ -292,6 +292,8 @@ void AudioStreamPlayer::_validate_property(PropertyInfo &property) const {
 
 		property.hint_string = options;
 	}
+
+	Node::_validate_property(property);
 }
 
 void AudioStreamPlayer::_bus_layout_changed() {