Add setting to increase station catchment radius.

Update acceptance and refresh screen when catchment settings change.

src/road_gui.cpp

@@ -984,6 +984,7 @@ struct BuildRoadStationWindow : public PickerWindowBase {
 		this->DrawWidgets();
 
 		int rad = _settings_game.station.modified_catchment ? ((this->window_class == WC_BUS_STATION) ? CA_BUS : CA_TRUCK) : CA_UNMODIFIED;
+		rad += _settings_game.station.catchment_increase;
 		if (_settings_client.gui.station_show_coverage) {
 			SetTileSelectBigSize(-rad, -rad, 2 * rad, 2 * rad);
 		} else {