#3 Indexed saving support is broken

[Anonymous]

both indexed animation and indexed plain picture (ie ordinary PNG) saving are broken.
the picture seems to be written in this way
* only the bottom layer is saved
* record index #0 if the pixel == 0, otherwise 1.

rgb version, looks fine:
http://img.photobucket.com/albums/v449/neota/zasni/jbanol-rgb.png

indexed version, weirded:
http://img.photobucket.com/albums/v449/neota/zasni/jbanol.png

I've also tested on other images with same kind of results.