Make it possible to receive MIDI directly from device

[Benjamin Klum]

• Add "MIDI device" dropdown to all sources
• Options should be all available MIDI devices plus "<VST MIDI input>"
• That way we can use ReaLearn also without needing to arm the track and assigning it a MIDI input

[Benjamin Klum]

re #129 Make it possible to receive MIDI directly from device

→ <<cset c959ea53252d>>

[Benjamin Klum]

re #129 Small UI improvements

→ <<cset a1712b66c7fb>>

[Benjamin Klum]

re #129 Auto-detect good setting for "Send feedback only if track armed"

• depending on MIDI control input
• only if "Auto-detect settings" enabled

→ <<cset 09a576ec25ff>>