Allows configuring the width of the coast in tropic maps that generates as tropiczone_normal before the desert kicks in, it does this by creating two additional arrays which house the coordinates to create a filled circle of radius of 19 tiles, and 25 tiles. the default creates a radius of 13 tiles.

I'd eventually like to add an Extra Large setting but manually creating the array of coordinates is horrible.

I wedged this setting in beside the setting for tropic width around rivers despite it not fitting into the rivers/lakes category because it still feels the most relevant place for now.

src/settings_gui.cpp

@@ -2108,6 +2108,7 @@ static SettingsContainer &GetSettingsTree()
 				rivers->Add(new SettingEntry("game_creation.river_route_random"));
 				rivers->Add(new SettingEntry("game_creation.rivers_top_of_hill"));
 				rivers->Add(new SettingEntry("game_creation.river_tropics_width"));
+				rivers->Add(new SettingEntry("game_creation.coast_tropics_width"));
 				rivers->Add(new SettingEntry("game_creation.lake_size"));
 				rivers->Add(new SettingEntry("game_creation.lakes_allowed_in_deserts"));
 			}