Support for pixel format and dithering

[JoHuang]

Reference link:

https://www.codeandweb.com/texturepacker/documentation/texture-settings#pixel-format---opt-pixelformat https://www.codeandweb.com/texturepacker/documentation/texture-settings#dithering---dither-type-dithertype

I would like to ask for the direction (some keyword or some libs to help with) to add these 2 features. Maybe I can help with it.

Thanks