[pygame] colorspace and other vision functions, where do they belong?

["Nirav Patel" <olpc@xxxxxxxxxxxxxx>]

Hello all,

I've added support for outputting different colorspaces from the
camera, and a Mask.get_centroid() to my pygame branch:
http://git.n0r.org/?p=pygame-nrp;a=summary

With the functions I'm writing now, I'm not sure what modules they
would belong in, or if they should be in a new module.  The functions
are things like converting the colorspace of a whole Surface, and
computing optical flow between two surfaces.  It makes sense that the
colorspace stuff would go in the color module, except that that module
is currently just for the Color class.  Optical flow could go in
transform, but it's not really a transform (though neither is
threshold, which is in it).

The colorspaces function would basically be as follows:

colorspace(Surface, colorspace, colorspace) returns Surface, where the
starting and ending colorspace is "RGB" "YUV" or "HSV".

Nirav