This release mostly revamps the PaletteReducer-related classes, such as FastPalette and QualityPalette, to be much simpler, and makes the FastSomething classes (like FastGif and FastPNG8) almost only differ by using FastPalette as their default. This allows the FastGif and FastPalette classes to be used on GWT, though they aren't actually much faster now (they may look different with some palettes, which could be useful).
FastPalette mostly differs in its color difference metric now, which is about the same as what PaletteReducer used before. Similarly, QualityPalette uses a better color difference metric, and PaletteReducer uses something similar but with some calculations done beforehand and cached. PaletteReducer and QualityPalette tend to perform similarly, but so does FastPalette, so the appearance may be all that sets them apart. This updates the WREN dither, changing how it clamps diffused error so that large flat areas are less common. It also updates LOAF, using a generally-better version that I had been testing in another repo (ColorWeaver) for a while. A few other dither algorithms may have changed.
I think this is generally a nice set of improvements; I hope you agree!