When dealing with png data that has less than 8 bits per pixel, round
up to the next byte when allocating per row buffers and streamers. This
fixes decoding odd sized PNGs with less than 8 bits per pixel.
Also added a test page with some odd sized palleted PNGs.
The sniff method is intended to be used for content sniffing. It should be a
cheap test to rapidly rule out whether a candidate image can be successfully
decoded. For the GIF and PNG implementations it simply attempts to decode the
image header, returning true if successful and false if not.
You can now #include <AK/Forward.h> to get most of the AK types as
forward declarations.
Header dependency explosion is one of the main contributors to compile
times at the moment, so this is a step towards smaller include graphs.
