[ENCHANCEMENT] Quality of Life: Show active zones accounting for instrument level

[spessasus]

Hi Davy,

first of all, thanks for implementing #199, it's great!

Though, I think we could make the algorhitm that lights up zones when I press a key better.

Take a look at GeneralUser GS 2.0.1 Preset Standard:

As you can see, all the zones light up, when they shouldn't. Only the Standard Kick 3 Instrument is actually playing.

For example, Standard Kick 2 only accepts key 35:

but it still lights up when I'm pressing key 36.

This QoL would make it way easier to find single-key instruments.

What do you think?