Allow footprints to generate archetype buildings

[PRemmen]

What is the problem?

• In one of the last releases we stopped support of CityGML due maintenance reasons,
• so currently no detailed geometry can be implemented in TEASER

Why do we want to solve it?

• However in projects we often see that footprints of buildings are available (e.g. masterplan)

How do we want to solve it?

• I'll try a light-weighted approach as also described in https://github.com/RWTH-EBC/TEASER/pull/570 where we do not support the geometry processing itself but define the orientation, tilt and area of all walls and windows.
• I'll also add an example how to process data from geojson (e.g. from QGIS)

DISCLAIMER: due date for merge (with unit tests, documentation, example, ...) can take a while