This allows us to use various framebuffer settings easily. Now the GPU
accelerated CLUT8 surface implementation does not need to query former
framebuffer state anymore.
This is basically an interface extracted from Texture without any knowledge
about any actual implementation, except for copyRectToTexture, fill, and
dirty rect handling. These are convenient helpers.
This mode should *not* be used by any new engines/code. If someone is going
to use it and says it works with the OpenGL output, please make them wear a
red uniform and beam them onto a remote planet.
This is mostly aimed at old graphics chips. For example, wjp's old laptop
only supports 1024x1024 textures but has a 1280x800 screen. Switching to
fullscreen would create a bigger overlay than supported. Now it will get
limited to an smaller resolution and then scaled too.
Alternatively we could think of tiling surfaces into textures. But then
handling scaling would be more complicated since it might result in
artifacts on texture tile borders.
