More figures from simulation report

[BoPeng]

We have this time_vs_size.R script to produce figures like this, which however cannot show information such as number of people quarantined, or number of people in each subpopulation etc.

I think the following could better present the information

|
| - - 
|.     - --- 
|                --- - --- 
|                                   ---- (number of remaining replicates)
|
|. ----
|.          -----  95% percentile for population size of remaining replicates)
|  x
|    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx average population size
|
|. ---------- 5% percentile for population size of remaining replicates)
| ------------------------------------------------------ > time

This figure can be customized/expanded to list all statistics, or multiple statistics, and not limited to population size.

Note that the scale of y-axis are different for number of replicates, but it can have its own scale or use a y-axis to the right.

[BoPeng]

https://github.com/k-sys/covid-19/blob/master/Realtime%20R0.ipynb has some example on plotting confidence interval, see the 'fill_between' function.