* Update PNG decoding to use palette that is passed around, instead of an
instance variable on the decoding module.
This fixes some issues around transparency, which were fixed in ChunkyPNG
before: wvanbergen/chunky_png#112
Changes are not available but here is a few from commit log:
* Add euclidean_distance_rgba method.
* Fix crash bilinear upsampling tall images.
* Fix bilinear upsampling correctness.
* Bilinear resampling in C.
* Removed debugging printf.
* Set bounds correctly, add tests.
* Store pixels in uint32_t instead of long.
Saves space and works on 32-bit systems
* Bump chunky_png dependency to 1.2.7.
* Bilinear resampling in C.
* Removed debugging printf.
* Set bounds correctly, add tests.
* Store pixels in uint32_t instead of long. Saves space and works
on 32-bit systems
* Bump chunky_png dependency to 1.2.7.
