Switch for ASID/RESID output

[micheldebree]

• Alt-o toggles ASID/RESID
• Output device shown in status bar
  • Mouse clicking the status also switches
• No switch to ASID if the MIDI port is not open (when there are no MIDI devices for instance)

P.S. I did not do a nullptr check on m_ASID because imo it will never be null