core: Replace homegrown queue with GLib's
core: Replace homegrown queue with GLib's

Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,Tarnyko/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Tarnyko/rygel,Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,jku/rygel,luisbg/rygel,jku/rygel