Treemap Feature: Show Budget calculated per head

[Lisa-Stubert]

The treemap could be extended by a function, so that one can select whether the monetary values are to be indicated as total values or as calculated per capita. In the district display, the values would then be calculated on the district population.

[vogelino]

We need:

• Data for Berlin and individual Bezirke
• Base on filter grab the population amount and calculate the per-head value
• Add filter to UI (Find an elegant way)