Improve lighting of entities.

Pass correct natural & artificial light to the shaders
Use natural/artificial light ratio for correct rendering of shadows

client/shaders/object_shader/opengl_fragment.glsl

@@ -471,7 +471,7 @@ void main(void)
 	color = base.rgb;
 	vec4 col = vec4(color.rgb, base.a);
 	col.rgb *= varColor.rgb;
-	col.rgb *= emissiveColor.rgb * vIDiff;
+	col.rgb *= vIDiff;
 
 #ifdef ENABLE_DYNAMIC_SHADOWS
 	float shadow_int = 0.0;