#547 UAEGfx 8bit mode makes bitmaps 8planes deep, regardless of requested depth.

[Kalamatee]

As the Title,

UAEGfx 8bit display modes always makes bitmaps 8bit deep, regardless of requested depth. This confuses anything expecting the correct depth.

An example of this is setting the screenmode to a depth of 4, which results in the screen still showing 256 colors.