3D Primitives Vocabulary and Alignments to IFC, CityRDF and X3D

[situx]

This pull request starts to consolidate the following things:

1. A vocabulary simply called "Simple Features 3D" for 3D primitives common in other 3D vocabularies
   • Curve Types as extensions to the Simple Features Vocabulary (e.g., BSplineCurve)
   • Surface Types as defined from different curves (e.g. BSplineSurface)
   • 3D Primitives in use in other 3D formats: e.g., Cone, Cylinder, etc.
   • Literal types to encode common 3D types Triply Use Case 1: Support for GLTF and other 3D formats #583
   • Material and Texture classes, which may or may not be replaced by CityRDF Appearance Module see Triply Use Case 2: Support for textures #584
2. Alignments to:
   • IFC also to collect concepts for the IFC Profile Triply Use Case 8: GeoSPARQL profile for IFC #590
   • X3D Web3D and X3D Ontology #571

Missing points:

• Are all geometry types included in this vocabulary?
• Did we cover all relevant literal types?
• Is the naming appropriate?
• Any additions to the alignments?