git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2697 92316355-f0b4-4df1-b90c-862c8a59935f

* stock.c: start working on stock image generation; for instance:
      pipi pipi:bayer64 -o image.png
    will generate a 64x64 Bayer dithering pattern and save it to image.png.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2695 92316355-f0b4-4df1-b90c-862c8a59935f