CityGML 3.0 encoding support

Summary

While CityGML 3.0 data can be parsed by CityDoctor2, the internal model is designed for the data model of CityGML 2.0. Most notably, the LOD definition received fundamental changes, dropping LOD-level 4 and allowing every feature type to have indoor elements (with their own LOD-level) regardless of their outdoor LOD. Additionally, the LOD now only affects the spatial representation, uncoupling it from the degree of semantic decomposition and allowing the use of thematic surfaces, openings and furniture at every LOD.

What is the function?

Rework the internal data model to fully support the CityGML 3.0 encoding model.

Why is it requested?

CityGML 3.0 has been recently declared by OGC as the offical latest version of the CityGML standard. Thus the rework is necessary to reflect the actual encoding of the data used by CityDoctor2's users, and prevent issues and errors arising from the mismatched model encoding.