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

Fixes:

• Call setParserForNextElement for BLDG_BuildingPartNode
  • Fixes "" being ignored when occurring directly under a ""

Models fixed 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

[mlavik1]

Sorry - messed up the PR.. will make a new one