[amo] +/- folds dev. - not group trk when tr. head select

[forge]

I have mapped the track headers to keys on my computer keyboard and when I select the track and try and open/close the group track with the +/- keys it folds/unfolds the first device on the track instead - but now that we have the ability to map keys to the device itself I would just map to the device instead to fold/unfold it