Visualize OSM element geometry

[Robbendebiene]

Todo:

• [x] Display basic shapes: dot, polyline, polygon, multi-polygon
• [x] Fix some polygon/ring building in GeometricOSMElement
  • Ring building works correctly, however the retrieved data is incomplete. It misses ways and nodes that are necessary to build the multipolygon because they lie outside of the queried bounding box.

Postpone:

• [ ] Revisit center point calculation for Polygons
• [ ] Display direction of polylines