First deocding fix for #53 , rendered image is incorrect.
Removing some debug print
Got back correct chroma dequantization for progressive JPEG
Add reading of delays without breaking the existing type signatures.
Break delay reading out into a separate function instead of mixing it with the frame decoding.
Merge pull request #59 from bit-shift/gif-delay

Add reading of gif frame delays without breaking the existing type signatures.
Merge pull request #57 from iger/master

comment changes
Passing through images with inverted color doesn't seem right
Add saving support for YA8 and YA16 images

It seems to work, but it still does not specify ExtraSamples
tag to state that stored data is in fact an alpha channel.
See bug #56 .
Add reading of YA tiff images

This code does not check that the extra channel is in fact
a transparency channel