[Gtkradiant] Realtime lighting approach issues.

[Hydra]

> Simulating Q3Map's lighting in Radiant (or ZHLTRad's lighting for
Half-Life) using pixel shaders and/or crude lightmap
> approximation doesn't do the mapper any favors, IMO.

yup, this is all good stuff, but don't forget to leave it open ended enough
so that we can add support for halflife lighting (and other games) without
having to re-code everything.

Whatever we do for this we need to make the lighting code into a MODULE,
rather than a statically linked lib.

Out of the two methods, method 1 would be simplest enough for adding
multiple game support as you'd just have to write a lighting module for each
game and replace as required.

I must admit that I don't really know much about all this lighting stuff
though.

Hydra