some errors in the shader code

I made some errors in the shader code
Firstly - I think it's better:

shader lights[] = getlights("category",Category);

than:

getvar(lights[i], "__category", __category);

        if(__category == Category) {
            push(categoryLights, lights[i]);
...............................

Secondly - to call the shaders in construt () method

- generally a bad idea if we want to use pixar relighting technology.

I think normally calling light co-shaders in lighting() method.