[Gzz] 12th & 13th (jvk)

[Janne Kujala]

12th & 13th: fisheye and paper basis demo hack work

Visualising texture combining by clamping the texture coordinates
and sliding the textures through each other does not work as expected
unless the textures have a border of constant color.
There is a border parameter to glTexImage2D, but is there any
way to get the desired clamping without modifying the texture 
images?

        jvk