Exposes the "interpolated" flag on nodes via a property, physics_interpolation_mode.
Mode can be INHERIT, OFF and ON. This makes it easy to turn off interpolation for nodes in the editor, versus via code. - lawnjelly
0ab077fcef
This is already done in `Node.add_child()` documentation, but
this copies the note in `Node.owner` for good measure.
(cherry picked from commit be1acf3b92b8b7104fe4d1fab9fbd2a28400ff95)