Rename internal API sixel_apply_palette to sixel_dither_apply_palette
Introduce a new member for dithering context object: pixelformat
Introduce new API: sixel_dither_set_pixelformat
Use dither->pixelformat internally
convert pixelformat in sixel_dither_apply_palette
Rename functions prefixed by 'LSQ' to sixel_quant_xxx
Pass pixelformat instead of depth to sixel_quant_make_palette
Merge branch 'develop' into feature-15bpp-processing-internally
Add missing parameter type definition
Skip memcpy only when pixelformat is RGB888
Reduce working memory allcation size during prepare histogram
Prevent memory access violation
Minor style improvement
Merge branch 'feature-15bpp-processing-internally' into feature-load-paletted-input
Chenage symbols of enum pixelFormat
Merge branch 'develop' into feature-load-paletted-input
Add paletted PNG images
Support paletted input
Style improvements
Retrive pixelformat from png loader