CityGML 3.0: Add support for missing elements

[mlavik1]

Hi. We needed to support a wider range for CityGML 3.0 datasets, and I encountered some issues due to unimplemented elements. Here's a PR fixing those.

Relates issue: #89

Main additions:

• gen:GenericOccupiedSpace
  • sample model
• gen:GenericUnoccupiedSpace
• gen:GenericLogicalSpace
• tran:Intersection
• tran:Section
• tran:Waterway
• bldg:buildingConstructiveElement
  • sample model
• bldg:buildingRoom
  • sample model
• relativeGeometry
  • CityGML 3.0 adds "relativeGeometry" to ImplicitGeometry.
• con:fillingSurface
• con:WindowSurface
• con:DoorSurface

Fixes:

• Call setParserForNextElement for BLDG_BuildingPartNode
  • Fixes "bldg:buildingPart" being ignored when occurring directly under a "bldg:Building"

Models fixed/improved by this PR:

• cube.city.zip
• DenHaag2.zip
  • CityGML converted form CityJSON file from this website, using citygml-tools
• Rotterdam2.zip
  • CityGML converted form CityJSON file from this website, using citygml-tools
• CityGML 3.0 dataset for Rotterdam, from here
• CityGML 3.0 dataset for Helsinki, from here
• CityGML 3.0 dataset for Espoo, from here
• https://github.com/tum-gis/citygml3.0-transportation-examples/blob/master/Simple%20Intersection/data/cityGML3_transportation_simpleIntersection.gml
• https://github.com/tum-gis/citygml3.0-transportation-examples/blob/master/Streetspace%20Model%20of%20New%20York%20City/data/CityGML3_Transportation_NYC.zip
• Also Railway_Scene_v3.gml, but that relies on Don't throw runtime error if endElement is called without a bound ele… #93 , and CityGML 3.0 texture support #94 for textures

[mlavik1]

Hi again @jklimke . I just updated my PR with some more changes. This should be my last change.
I added support for relativeGeometry (for ImplicitGeometry in CityGML 3.0), as well as some other surface types.

Feel free to let me know if you notice anything you want me to change.