MDL Roll Playback

Currently, 3-line tremolos notate sort of like this... 1 line is 8th notes, 2 lines is a sustained buzz, and 3 lines is 32nd notes

For MDL, I would propose changing 2 lines to 16th note doubles and 3 lines to sustained rolls

(sustained rolls aren't literally buzzed sixteenths, the buzz roll sound just needs to sustain the duration of the note, this already works well so there is always a good roll sound no matter the duration)

 - Other than rolls, there are some minor things that I would recommend to improve
      1. Automatically make any unnaccented notes in MDL instruments playback softer
      2. lower the volume of the sound of inputting notes