Merge branch 'master' into jgrpp

# Conflicts:
#	regression/regression/result.txt
#	src/aircraft_cmd.cpp
#	src/airport_gui.cpp
#	src/articulated_vehicles.cpp
#	src/console_cmds.cpp
#	src/date_gui.cpp
#	src/engine.cpp
#	src/genworld_gui.cpp
#	src/gfx_layout_fallback.cpp
#	src/group_gui.cpp
#	src/hotkeys.cpp
#	src/network/core/tcp_connect.cpp
#	src/network/core/tcp_listen.h
#	src/newgrf.cpp
#	src/newgrf.h
#	src/newgrf_engine.cpp
#	src/newgrf_gui.cpp
#	src/newgrf_station.cpp
#	src/openttd.cpp
#	src/order_gui.cpp
#	src/os/macosx/osx_main.cpp
#	src/pathfinder/yapf/yapf_node_rail.hpp
#	src/rail_gui.cpp
#	src/saveload/afterload.cpp
#	src/saveload/cargopacket_sl.cpp
#	src/saveload/linkgraph_sl.cpp
#	src/saveload/station_sl.cpp
#	src/script/api/script_industrytype.cpp
#	src/settings.cpp
#	src/settings_gui.cpp
#	src/settings_table.cpp
#	src/settingsgen/settingsgen.cpp
#	src/station.cpp
#	src/station_cmd.cpp
#	src/strings.cpp
#	src/timer/timer_game_calendar.cpp
#	src/timer/timer_game_calendar.h
#	src/timer/timer_manager.h
#	src/timer/timer_window.cpp
#	src/timetable_cmd.cpp
#	src/toolbar_gui.cpp
#	src/town_cmd.cpp
#	src/town_gui.cpp
#	src/train_gui.cpp
#	src/vehicle_cmd.h
#	src/vehicle_gui.cpp
#	src/viewport.cpp
#	src/widgets/dropdown.cpp
#	src/window_func.h
#	src/window_gui.h

src/gfxinit.cpp

@@ -546,12 +546,13 @@ void GfxLoadSprites()
 	DEBUG(sprite, 2, "Completed loading sprite set %d", _settings_game.game_creation.landscape);
 }
 
-bool GraphicsSet::FillSetDetails(IniFile *ini, const std::string &path, const std::string &full_filename)
+bool GraphicsSet::FillSetDetails(const IniFile &ini, const std::string &path, const std::string &full_filename)
 {
 	bool ret = this->BaseSet<GraphicsSet, MAX_GFT, true>::FillSetDetails(ini, path, full_filename, false);
 	if (ret) {
-		IniGroup *metadata = ini->GetGroup("metadata");
-		IniItem *item;
+		const IniGroup *metadata = ini.GetGroup("metadata");
+		assert(metadata != nullptr); /* ret can't be true if metadata isn't present. */
+		const IniItem *item;
 
 		fetch_metadata("palette");
 		this->palette = ((*item->value)[0] == 'D' || (*item->value)[0] == 'd') ? PAL_DOS : PAL_WINDOWS;