This just shuffles around the streamwidget a bit. The RoleWidget child class is the
exception, so try and gear things around SinkInput/SourceOutput widgets more to
save repeating the same code too much.
This abandons the combo box approach an instead partially reverts to the popup.
We now display a suffix after the stream title saying " on <device>" or " from <device>"
where the <device> part looks like a hyperlink and, when clicked, shows the popup to change the device.
If there is only one device available, we suppress the whole thing and thus avoid confusion.
Rafał Mużyło