Split opennet routing table into short links and long links (refactored)

This is similar to split-opennet-routing-table-original, which is better tested, but cleaned up history and with some minor opennet refactoring included. It does appear to work.
`nodeToAddNow == null`? What does that indicate? Am I missing context? I see no calls with `null` explicitly provided as `nodeToAddNow`. A logging line below suggests `null` means no node. What am I missing?