Merge branch 'master' into jgrpp

# Conflicts:
#	src/company_cmd.cpp
#	src/core/overflowsafe_type.hpp
#	src/economy.cpp
#	src/engine_base.h
#	src/ground_vehicle.cpp
#	src/group_gui.cpp
#	src/industry_cmd.cpp
#	src/industry_gui.cpp
#	src/newgrf_commons.cpp
#	src/newgrf_engine.cpp
#	src/newgrf_industries.cpp
#	src/newgrf_object.cpp
#	src/newgrf_roadstop.cpp
#	src/newgrf_station.cpp
#	src/rail_gui.cpp
#	src/road_cmd.h
#	src/road_gui.cpp
#	src/saveload/afterload.cpp
#	src/script/api/script_log.cpp
#	src/script/api/script_log.hpp
#	src/settings_gui.cpp
#	src/settingsgen/settingsgen.cpp
#	src/station_cmd.cpp
#	src/station_cmd.h
#	src/station_gui.cpp
#	src/strgen/strgen.cpp
#	src/string_func.h
#	src/string_type.h
#	src/table/settings/network_private_settings.ini
#	src/tests/math_func.cpp
#	src/textfile_gui.cpp
#	src/timetable_gui.cpp
#	src/town_cmd.cpp
#	src/vehicle.cpp
#	src/waypoint_cmd.cpp
#	src/waypoint_cmd.h
#	src/widgets/dropdown.cpp

src/strings_func.h

@@ -264,9 +264,9 @@ public:
 
 	/**
 	 * Get the next string to search through.
-	 * @return The next string or nullptr if there is none.
+	 * @return The next string or nullopt if there is none.
 	 */
-	virtual const char *NextString() = 0;
+	virtual std::optional<std::string_view> NextString() = 0;
 
 	/**
 	 * Get the default (font) size of the string.