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/fios.h

@@ -126,8 +126,7 @@ public:
 	 */
 	inline FiosItem *Append()
 	{
-		/*C++17: return &*/ this->files.emplace_back();
-		return &this->files.back();
+		return &this->files.emplace_back();
 	}
 
 	/**