Improve playback for rolled chords on percussive instruments (& maybe piano)

In the discussion for my notes on how rolled marimba chords cause playback to choke up , I made a note that the current implementation of rolled percussive & piano chords is quite unmusical, since MuseScore plays back the whole chord rapidly due to the tremolo symbol.

It's easier to explain the problem and my proposed solution by example, so see the attached file to hear what the problem is and read my solutions. The most basic way to describe my fix for instruments that get marked as needing is to divide chords up into groups of notes and then rapidly alternate between those groups.

Although I first thought of this specifically with mallet percussion in mind, it also is applicable to rolling two drums at once (for example both your floor toms on your kit), and likely also applicable to the piano (& other keyboard instruments).

The only thing I'd add that I didn't mention in the proposal in the file is that it would also be useful to change roll patterns mid-song (ex: a marimba solo that wants you to roll 1-2-3-4 at the beginning and 4-3-1-2 at the end for subtle contrast between the halves).