Bug: buzzing noise breaks down if trompette is low

[bazmonk]

Currently the root note of the buzzing sound/channel is kept in sync with the trompette channel. This makes sense, but if the trompette is set to a low note, the buzzing sound slowed down to that frequency breaks down and stops sounding like a buzz.

Since the buzz is otherwise independent of the "trompette" channel, that channel is sorta just a second drone. It would be nice to be able to use it as a drone lower than one may realistically use as a trompette string on a real gurdy.

So...

• Research - I need to try out all the provided drone sounds and find the range they're usable. Determine a range that works for all of them.
• Fix - Add logic that sets the buzz note to a higher octave or harmonic if the trompette is set below that range.

[bazmonk]

This has been addressed in the above commit.

When tunings are set, code is in place that bumps the buzz note down/up an octave at a time until it is between D4/D5 (I think… not looking at the code right now).

This restriction doesn’t apply to transposing, so that can still potentially take it to a funky note. I don’t want to limit too much, though, so I’m calling it OK for now. It prevents it from getting ridiculously low or high at least.