Add curve to show ICU census and admissions

[Mdraugelis]

The user needs a way to estimate the ICU bed needs from the output.

Option 1: (downside: makes the plot too cluttered) Either update the Vent Census / Admit Graph to include the median ICU line.

Option 2: (Three columns of plots might be to small to view) add a third column for ICU Census / Admit Graph.

My preference is for option 2.

[cjbayesian]

I have heard from various folks that ICU ~ Vent.