[fixed] Player setup colour preview doesn't work 1.0.18

[Enjay]

The player preview window in player setup remains the default green regardless of how the RGB sliders are set. The in-game player changes, it's just the setup preview that doesn't work. Zdoom 2.1.3 is fine, it seems to be just a GZdoom thing.

[Graf Zahl]

You can blame Grubber for this. His new code doesn't handle the player texture properly and instead resorts to a software only hack to handle it. I'll have to rewrite some of it completely to make it work again.