By: Mark Glennon*   It seems simple enough that we should have figured out how to get it long ago — an economy where people trade services and goods among each other rapidly enough and at high enough value that each individual can live in dignity. Yet, in Illinois and much of the world, that remains elusive, and it’s that central failure that’s key to the downward spiral of the middle class and sustained poverty.   There’s no need to review the facts about unemployment and low wages. Particularly in Illinois, those who claim we are coming back are asking