Shadows and spot lights with ShaderBuilder

@NasimiAsl,

Shadows and spot lights do not work on the ground. I gave you an example on the playground.

http://www.babylonjs-playground.com/#E6OZX#87

terrain.material.specularColor = new BABYLON.Color3(0.5, 0.5, 0.5);
terrain.material.specularPower = 64;

do not work also

And In fact the lighting has no effect on the ground, so the textures are pale.

Thanks