[png-mng-implement] Is my dithering code working do you think?

[Adrian M. <ad...@ne...>]

You can see the output here:

http://transpero.net/nevermind/?p=12

Would welcome views on whether or not these are reasonable results or if
people think that they indicate something is wrong in the code (aside
from the fact it is so slow as to be useless - I can always try to fix
that)