Bronze, Silver and Atherean palette for Bucks Shop#48

Using the Gold palette shader logic add some additional colors as buck shop exclusives. A bit of a lower development cost way to inject a lot of new cosmetics into the game without bloating the coin store. This also gives a way for long term supporters to dump spare bucks beyond gifting. Along with giving players more opportunity to use metallic skins that may not prefer gold or only want a few a la carte.