When a wired headset is connected, show an option to play through the loudspeakers

[mardy]

I don't think this has already been requested so far, and indeed it's hard to find a plausible use-case for this, but once we have the FM radio in place, it might make sense to add such an option: people might have the headphone connected just in order to be able to tune the FM radio, but will want to have all sounds coming out though the speakers.