Sarien/Hires Badness

Sarien's hires mode causes some behavioural glitches, and should be removed in favour of leaving these Scale2x-style graphical enhancements to the ScummVM backends, especially since it can be made optional at that point.

The primary problem comes from AGI_Specifications/Overview#Priority AGI's priority screens, which control how the background scenery and the movable objects interact. For the uninitiated, you can think of it as a sort of "depth channel" (by analogy with an alpha channel).

AGI is a fairly touchy engine, and really requires pixel-perfect rendering internally; the hires mode thus causes a few problems.

Here's a couple of screenshots from Space Quest 2 to demonstrate the kind of things that go wrong: