Merge branch 'master' into jgrpp

# Conflicts:
#	.github/workflows/ci-build.yml
#	src/ai/ai_gui.cpp
#	src/blitter/32bpp_optimized.cpp
#	src/blitter/32bpp_simple.cpp
#	src/blitter/32bpp_sse2.cpp
#	src/blitter/8bpp_optimized.cpp
#	src/blitter/8bpp_simple.cpp
#	src/blitter/null.cpp
#	src/blitter/null.hpp
#	src/company_gui.cpp
#	src/game/game_gui.cpp
#	src/genworld_gui.cpp
#	src/gfx.cpp
#	src/gfx_func.h
#	src/graph_gui.cpp
#	src/industry_gui.cpp
#	src/linkgraph/linkgraphjob.cpp
#	src/network/network_gui.cpp
#	src/newgrf_debug_gui.cpp
#	src/openttd.cpp
#	src/pathfinder/npf/aystar.h
#	src/road_gui.cpp
#	src/saveload/order_sl.cpp
#	src/saveload/saveload.cpp
#	src/saveload/saveload.h
#	src/script/api/script_log.cpp
#	src/script/api/script_town.cpp
#	src/script/script_gui.cpp
#	src/settings.cpp
#	src/settings_gui.cpp
#	src/settings_table.cpp
#	src/settings_type.h
#	src/smallmap_gui.cpp
#	src/sortlist_type.h
#	src/spritecache.cpp
#	src/spriteloader/grf.cpp
#	src/spriteloader/grf.hpp
#	src/spriteloader/spriteloader.hpp
#	src/station_cmd.cpp
#	src/station_cmd.h
#	src/station_gui.cpp
#	src/strings.cpp
#	src/toolbar_gui.cpp
#	src/town_cmd.cpp
#	src/town_gui.cpp
#	src/vehicle_gui.cpp
#	src/vehicle_gui_base.h
#	src/video/opengl.cpp
#	src/video/opengl.h
#	src/widgets/dropdown.cpp
#	src/widgets/dropdown_type.h
#	src/window_gui.h

src/engine_gui.h

@@ -29,7 +29,7 @@ struct GUIEngineListItem {
 	bool operator == (const EngineID &other) const { return this->engine_id == other; }
 };
 
-typedef GUIList<GUIEngineListItem, CargoID> GUIEngineList;
+typedef GUIList<GUIEngineListItem, std::nullptr_t, CargoID> GUIEngineList;
 
 typedef bool EngList_SortTypeFunction(const GUIEngineListItem&, const GUIEngineListItem&); ///< argument type for #EngList_Sort.
 void EngList_Sort(GUIEngineList &el, EngList_SortTypeFunction compare);