Merge branch 'master' into jgrpp

# Conflicts:
#	.gitignore
#	CMakeLists.txt
#	src/3rdparty/optional/optional.hpp
#	src/group_cmd.cpp
#	src/industry_cmd.cpp
#	src/misc_gui.cpp
#	src/video/sdl2_v.cpp

src/saveload/waypoint_sl.cpp

@@ -192,8 +192,7 @@ static void Load_WAYP()
 	int index;
 
 	while ((index = SlIterateArray()) != -1) {
-		/*C++17: OldWaypoint *wp = &*/ _old_waypoints.emplace_back();
-		OldWaypoint *wp = &_old_waypoints.back();
+		OldWaypoint *wp = &_old_waypoints.emplace_back();
 
 		wp->index = index;
 		SlObject(wp, _old_waypoint_desc);