Cleanup in the D3D native pipeline

The native code has several places that could use a cleanup:

1. D3DLight defines the unused functions setColor and setPosition.

2. The HLSL files' parameter names are confusing, better names should be chosen for readability.

3. D3DMeshView constructor has a line
    ZeroMemory(lights, sizeof(D3DLight) * 3);
which is very possibly a cause for memory leak.