Fix memory leak.
Fix preferences window not updating when switching interfaces.
Various vfs_async fixes.
Migrate playlist from GList to List class.
Use standard C++ types.
libaudcore: Export mainloop API.
Use String() instead of null pointers.
Use decltype(nullptr) to avoid the need for <cstddef>.
libaudgui: Use true and false keywords.
Merge branch 'master' into gtk3

Conflicts:
	src/libaudgui/about.cc
	src/libaudgui/equalizer.cc
	src/libaudgui/infopopup.cc
	src/libaudgui/infowin.cc
	src/libaudgui/list.cc
	src/libaudgui/plugin-prefs.cc
	src/libaudgui/plugin-view.cc
	src/libaudgui/prefs-widget.cc
	src/libaudgui/prefs-window.cc
	src/libaudgui/scaled-image.cc
	src/libaudgui/status.cc
	src/libaudgui/ui_fileopener.cc
	src/libaudgui/ui_jumptotrack.cc
	src/libaudgui/ui_playlist_manager.cc
	src/libaudgui/util.cc