P0-A3: Part 542: World Builder

The issue with the planet textures and shaders at long distances from the origin should be fixed.

The solution was to actually encode the terrain height into a second mesh UV channel, and then simply read that data from the shader. This was a much more elegant and effective solution than performing a distance calculation in the shader itself.

I have still got quite a bit of work to do on the shaders, there are several shaders involved in terrain rendering, including water/ocean shaders, grass shaders, and the actually terrain shader itself, they will all need to be modified.