UX improvements for `section_edge`

[palinatolmach]

As suggested by @dkcumming, it'd be helpful to support the following two new features in section_edge:

1. In addition to the number of sections, support a max-depth-like parameter;
2. Support transitive sectioning, i.e., make section_edge work for every two nodes connected by a number of edges (e.g., for nodes 1 - 2 - 3, support section-edge 1 3).