Miscellaneous C++ conversion.
gtkui: Save and propagate column widths from the size-allocate event.
plugins: chase audtag changes
Revert recent libaudtag changes as they broke the build in addition to various other problems.
plugins: chase audtag changes
More audtag changes.
Merge remote-tracking branch 'origin/master' into gtk3

Conflicts:
	src/gtkui/ui_playlist_notebook.cc
	src/skins/ui_skin_load_ini.cc