[Fluxus] hint-normalize

[gabor papp]

hi,

fluxus rescales normals by using glEnable(GL_RESCALE_NORMAL). this does 
not work if there's nonuniform scaling. for example you can notice 
lighting problems with the following script. the two boxes are lit 
differently:

(clear)

(build-cube)

(with-primitive (build-cube)
     (translate #(2 0 0))
     (scale #(3 1 1)))

to fix this i added a new hint called (hint-normalize).

best,
gabor