Wish: Show city outlines

[pasky]

The GTK3 client has (default on) option to show city outlines, i.e. highlight edges of the parts of map that belong to a city's area.

For me, the game is very difficult to play without this as I usually try to find an "optimal tiling of cities" that haev gapless and non-overlapping city areas.

Active settlers unit also highlights the edges of its potential city area.

[rvid19]

Sounds interesting.