Partition area

[cbueth]

Add stats about partition area.

1. Find bounding
   Using osm relation when importing graph
2. Create voronoi cells
3. Add attribute to every node containing it's area shapely.area()
4. Sum area for the partitions
5. LTNs: shape & size using geopandas concave hull or boundary

[cbueth]

How-to:

1. Use osm relation outer boundary for total area and outer boundary, write to graph attributes of partitioner.graph.
2. For LTNs use geopandas concave hull or boundary, maybe with buffer, to determine boundary shape and are. With the shape Population density #64 should later be determined.