[BREAKING] ShaderMaterial no longer auto includes gamma, tonemapping and fog code

[mvaligursky]

ShaderMaterial used to automatically include the mentioned chunks, equivalent to:

            #include "gammaPS"
            #include "tonemappingPS"
            #include "fogPS"

Now that ShaderMaterial has grown into a more general system that initially intended, this has been removed.

If the user uses relevant code functions:

      vec3 fogged = addFog(colorLinear);
      vec3 toneMapped = toneMap(fogged);
      gl_FragColor.rgb = gammaCorrectOutput(toneMapped);

they need to include the relevant functionality into their shader