IfcRepresentationItem tree (topology and geometry branches)

Description of the proposal:
The tree branches into geometric and topological items. Topological items have a corresponding partner in the geometry tree e.g. IfcVertexPoint - IfcPoint, IfcPolyLoop - IfcPolyline etc.
Describe how it contributes to the objectives (https://github.com/buildingSMART/NextGen-IFC/wiki/Towards-a-technology-independent-IFC): Streamlining the geometry core.

Is this a proposal to 'add', 'remove' of 'change' entities in the schema (pick one):
remove
What do we win:
remove redundancies
What do we lose
topological representations
Schema impact:
less entities
Instance model impact:
less diversity
Backwards compatible:
almost, depending on which entities are using the items
Automatic migration possible:
should be possible (speaking from experience when parsing the entities)
Additional implications:

-
Note that not all points need to be satisfied!
Backwards compatibility and file size are not concerns.