This merges all mix operations into a COM_MixBaseOperation (naming could be better, but this way it corresponds to what's going on with math operations. Same was done with RenderLayers operations. Overall this gives 20% of bf_compositor library compilation time decrease. And it was rather annoying to have tens of files with just a single-line constructors anyway. TODO: - All Convert operations could also be merged into a single file, but that would require adding some ConvertBaseOperation to reduce code duplication (ideally). Leaving it unchanged for now. - Some operations' headers seems to be wrongly including MixOperation header, they need to include NodeOperation instead it seems. This is rather harmless, but would be nice to doublecheck on this eventually.