Settings GUI: Move day length factor to environment section

src/settings_gui.cpp

@@ -1904,7 +1904,6 @@ static SettingsContainer &GetSettingsTree()
 		{
 			accounting->Add(new SettingEntry("economy.inflation"));
 			accounting->Add(new SettingEntry("economy.inflation_fixed_dates"));
-			accounting->Add(new SettingEntry("economy.day_length_factor"));
 			accounting->Add(new SettingEntry("difficulty.initial_interest"));
 			accounting->Add(new SettingEntry("difficulty.max_loan"));
 			accounting->Add(new SettingEntry("difficulty.subsidy_multiplier"));
@@ -2122,6 +2121,7 @@ static SettingsContainer &GetSettingsTree()
 				treedist->Add(new SettingEntry("construction.tree_growth_rate"));
 			}
 
+			environment->Add(new SettingEntry("economy.day_length_factor"));
 			environment->Add(new SettingEntry("station.modified_catchment"));
 			environment->Add(new SettingEntry("station.catchment_increase"));
 			environment->Add(new SettingEntry("station.cargo_class_rating_wait_time"));