26w24b: Terrain Shader FPS improvement

So the per-triangle virtual textures turned out to be too complex, and the final gains too limited to justify the cost.

I decided to kill them and went back to the drawing board to deliver those much needed FPS improvements.

I tweaked and improved the terrain shader: we jumped from 70 to 95 fps (from 50 fps two months ago!). Still sensible gains!

The look will be a bit different, but it will actually look better from afar.

Planet Texture:

I also added a setting for the planet texture generation, which give planets a hd looks when viewed from space.

The new high settings makes the planets looks twice better!

Thanks for playing!