Allow player-naming of Network Cells

[ExcessionOz]

Allow players to name network cells (when cells are created, merged or split)

When using L to look at networks, only network numbers show up, with no corresponding display on the map as to what network is where.
A naming system for Network Cells would aid in finding cells that are of interest.
Optionally, show cell names (or numbers) on the map.

This was suggested in 2017 for V0.15, I am asking now since V0.17 and beyond is being planned/implemented.