[CsMain] still map lighting woes

[N. S. <a1...@al...>]

Hn, last attempt to understand a "bug" that I noticed when I started playing with dynamic 
lights:

(This map has a static light, but a very weak one, to intensify the effect)

http://www.clubotaku.org/Saturn/cslight.jpg

It seems like certain polygons, if large, go full bright. I tried splitting the large 
"floor" but it rarely works (and also depends if i'm using the software or OpenGL 
renderer). And also reducing the size of the polygon does not make it lighted. I'm 
currently using CS 0.94 r002.