cute_png.h Lookup Table Acceleration

[RandyGaul]

A while ago I made an attempt to use lookup table accelerator for decoding, and use the binary search decoder as a fallback if the code bitlength was beyond the lookup table's maximum size. I was attempting to mimic the lookup logic found in stb_image.h, but somehow I ended up introducing some bugs, and the lookup table is now unused.

Open up cute_png.h and search for "lookup" without case-sensitivity to easily find all the lookup table code.

The lookup table should be fixed up and used, eventually. This is a low priority task, so who knows when I will get around to it (if ever), but I'm writing it down here just so I don't forget.

If anyone else is interested in trying, feel free to take over and submit a pull request.

[RandyGaul]

Not worth the effort! Closing.