[fluxus] lighting fixes

[Dave Griffiths]

Hi all,

I've fixed some lighting bugs and added commands to support point,
directional or spotlights, and put support in for modifying all the
attenuation modes etc for GL lighting.

The api now looks like this:

(make-light type cameralocked)
(light-ambient id colvec)
(light-diffuse id colvec)
(light-specular id colvec)
(light-position id vec)
(light-direction id vec)
(light-spot-angle id angle)
(light-spot-exponent id exponent)
(light-attenuation id type setting)

See the docs for more details.

I'd quite like to let things settle now for a while and get a release
done, most things on my list are now new features - alpha sorting, glsl,
blobbies and more physics toys that can wait till after 0.10.

cheers,

dave