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/music.cpp

@@ -116,14 +116,14 @@ template <class Tbase_set>
 	return BaseMedia<Tbase_set>::used_set != nullptr;
 }
 
-bool MusicSet::FillSetDetails(IniFile *ini, const std::string &path, const std::string &full_filename)
+bool MusicSet::FillSetDetails(const IniFile &ini, const std::string &path, const std::string &full_filename)
 {
 	bool ret = this->BaseSet<MusicSet, NUM_SONGS_AVAILABLE, false>::FillSetDetails(ini, path, full_filename);
 	if (ret) {
 		this->num_available = 0;
-		IniGroup *names = ini->GetGroup("names");
-		IniGroup *catindex = ini->GetGroup("catindex");
-		IniGroup *timingtrim = ini->GetGroup("timingtrim");
+		const IniGroup *names = ini.GetGroup("names");
+		const IniGroup *catindex = ini.GetGroup("catindex");
+		const IniGroup *timingtrim = ini.GetGroup("timingtrim");
 		uint tracknr = 1;
 		for (uint i = 0; i < lengthof(this->songinfo); i++) {
 			const std::string &filename = this->files[i].filename;
@@ -133,7 +133,7 @@ bool MusicSet::FillSetDetails(IniFile *ini, const std::string &path, const std::
 
 			this->songinfo[i].filename = filename; // non-owned pointer
 
-			IniItem *item = catindex->GetItem(_music_file_names[i]);
+			const IniItem *item = catindex != nullptr ? catindex->GetItem(_music_file_names[i]) : nullptr;
 			if (item != nullptr && item->value.has_value() && !item->value->empty()) {
 				/* Song has a CAT file index, assume it's MPS MIDI format */
 				this->songinfo[i].filetype = MTT_MPSMIDI;
@@ -158,7 +158,7 @@ bool MusicSet::FillSetDetails(IniFile *ini, const std::string &path, const std::
 				 * the beginning, so we don't start reading e.g. root. */
 				while (*trimmed_filename == PATHSEPCHAR) trimmed_filename++;
 
-				item = names->GetItem(trimmed_filename);
+				item = names != nullptr ? names->GetItem(trimmed_filename) : nullptr;
 				if (item != nullptr && item->value.has_value() && !item->value->empty()) break;
 			}
 
@@ -179,7 +179,7 @@ bool MusicSet::FillSetDetails(IniFile *ini, const std::string &path, const std::
 				this->songinfo[i].tracknr = tracknr++;
 			}
 
-			item = trimmed_filename != nullptr ? timingtrim->GetItem(trimmed_filename) : nullptr;
+			item = trimmed_filename != nullptr && timingtrim != nullptr ? timingtrim->GetItem(trimmed_filename) : nullptr;
 			if (item != nullptr && item->value.has_value() && !item->value->empty()) {
 				auto endpos = item->value->find(':');
 				if (endpos != std::string::npos) {