[Fluxus] video capture

[gabor papp]

> (camera-tcoords vt)
> gets the texture coordinates of the camera image, this is required 
> because fluxus uses square textures, but camera and video images are
sorry, i meant power-of-two textures, and camera images are 
non-power-of-two.

committed some documentation to the video code, and a couple of new 
functions so images can be passed to other image processing modules.

(camera-width), (camera-height) return the width and height of the 
camera image.

(camera-imgptr) returns a tagged cpointer to the camera pixel buffer.

best,
gabor