Import town bridges over rails patch

Add setting (default off)

From: https://www.tt-forums.net/viewtopic.php?f=33t=76052

src/settings_gui.cpp

@@ -1776,6 +1776,7 @@ static SettingsContainer &GetSettingsTree()
 				towns->Add(new SettingEntry("economy.found_town"));
 				towns->Add(new SettingEntry("economy.town_cargo_scale_factor"));
 				towns->Add(new SettingEntry("economy.random_road_reconstruction"));
+				towns->Add(new SettingEntry("economy.town_bridge_over_rail"));
 			}
 
 			SettingsPage *industries = environment->Add(new SettingsPage(STR_CONFIG_SETTING_ENVIRONMENT_INDUSTRIES));