Expand naming RFC to consider Vertex mode and undirected edge mode

[ajfriend]

Naming collision/ambiguity concerns, off the top of my head:

• "topological" vertex vs geometric/boundary vertex
  • what naming convention would make this obvious to users?
• directed edge vs (undirected) edge
  • can we use "edge" to mean undirected edge without confusion with directed edge?

@nrabinowitz, just to justify diving into naming, yet again ;)

[RichardVasquez]

2 cents here, since things are going to break in 4.0, anyway.

Call a DirectedEdge a Vector, and an undirected edge, just an Edge, or a segment.

[nrabinowitz]

We already have a Vector internally (used in the internals of h3ToGeo and geoToH3). I think Edge was where we ended up for undirected edges, and DirectedEdge has a nice symmetry there. 🤷