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/3d/decal.cpp

@@ -160,6 +160,7 @@ void Decal::_validate_property(PropertyInfo &property) const {
 	if (!distance_fade_enabled && (property.name == "distance_fade_begin" || property.name == "distance_fade_length")) {
 		property.usage = PROPERTY_USAGE_NOEDITOR;
 	}
+	VisualInstance3D::_validate_property(property);
 }
 
 TypedArray<String> Decal::get_configuration_warnings() const {