[Audacity-quality] Rename Note tracks to MIDI tracks

[Peter S. <pet...@gm...>]

James wrote in a parallel thread (and sorry I can't find it right now) that
for 2.2.1
we should consider renaming Note tracks to MIDI tracks.

I support this idea - but I strongly think we should temporarily lift the
semi-freddo for this
and do it for 2.2.0.

My reasoning for this is that with 2.2.0 we are putting a much sharper and
bigger focus
on this with Audacity providing functioning MIDI playback for the first
time- and thus this
would be the ideal time to make the switch, I'm thinking.

AFAIK nothing else but importing a MIDI file is the only way to get a Note
track - so I see
no reason not to do this - the only question is: do we do it now?

Just my 2c-worth

Peter.