Add setting for map edge behaviour, and how to display area outside map

src/settings_gui.cpp

@@ -2414,6 +2414,7 @@ static SettingsContainer &GetSettingsTree()
 			}
 
 			environment->Add(new SettingEntry("construction.flood_from_edges"));
+			environment->Add(new SettingEntry("construction.map_edge_mode"));
 			environment->Add(new SettingEntry("economy.day_length_factor"));
 			environment->Add(new SettingEntry("station.modified_catchment"));
 			environment->Add(new SettingEntry("station.catchment_increase"));