Make biome variation more clear on maps

Sometimes it's hard to discern which biomes are on a map. For example savanna  and swamp biomes are the same green color as plains biomes, despite savanna grasses having a more brownish hue and swamps having a deeper green. The same for spruce forests, birch forests, and oak forests. Changing the maps to have more details colors showing biome variation would help explorers figure out which areas on their maps were which biomes without having to use named banners.