auto scale depth and stencil displays

[greggman]

brandon might have already done this but if not, it would be nice if you could view stencil and depth textures with level controls (min - max) settings that scale what's drawn. In other other words if you set min to 0.4 and max to 0.5 then colorDrawn = (depth - min) / (max - min)

Same for stencil except integer ranges so it's easy to visualize a stencil with only 0 and 1 values.

Then, ideally, an "auto scale" option where the debugger finds the min max values in texture and sets min max for you automatically.