Make demo with long population timeseries

[jgaffuri]

There are various dataset on total population for long timeseries:

• https://hub.worldpop.org/geodata/listing?id=64
• NO
• incoming JRC dataset from 1961

We could make a demo showing this type of dataset. Based on https://ec.europa.eu/eurostat/web/gisco/geodata/grids
Maybe timeslider for year
For population change, pair of years should be selected dynamicly as well
Plus two additional styles:

• One based on timeseriesstyle - https://eurostat.github.io/gridviz/docs/reference.html#time-series-style
• One showing the year of maximum (and/or minimum) population