Add RiemannSurfacePathFactory stub.

Add a stub for the RiemannSurfacePathFactory class and update
the documentation syntax of the function brought over from the
old, non-refactored code.
RiemannSurfacePathPrimitve can be added.

This is untested, but you can now add Riemann surface paths
together. Mathematically, this means you can extend paths by other
paths, as long as the starting and ending points / places match.
Programmatically, this creates a RiemannSurfacePath object from
two RiemannSurfacePathPrimitives.

This makes the notion of a path primitive having its "segements"
attribute set to "[self]" become very important.
Checkpoint refactor debugging.

The code compiles yet verification and debugging is not complete.
Checkpoint refactor debugging.

Added two new files.