Initial commit
Filter only scanlines
Clean and comment
Mutate palette to avoid LSB stegano leak
Add header
Minimize PLTE scanline corrections
Adjust idx IDAT size for libpng compatibility
Supports palettes with n colors
Find_closest_idx()
Accept extra png as palette
Rename mergeRGB4 in mergeRGBi
Merge png.py
Accepts PNGs of different sizes

Ideally take 3*rgb_width=idx_width
E.g. with ratios 1:1.75 <> 1.75:1
New src images
Add pngfixcrc.py