New version for Gordon Kart 2D

Howdy, pardners!

I published a new version for Gordon Kart 2D (prototype started in early 2020, even older than the 3D version). Now that I think of it, I don't think I publicly distributed the first 2D version before. Oh well, now it's out!

I ported it to Godot 4 and added an airplane mode, which is exactly what it sounds like in the context of driving a vehicle.

For now it's for Windows and Linux only.

Happy driving/soaring everyone!