advanced_arpeggiation function

[caseywescott]

Implement Custom Arpeggio Patterns

Allow user-defined arpeggio patterns (e.g., up-down, random, etc.).

function should look kind of like this:
fn custom_arpeggiate(self: @midi, pattern: ArpPattern) -> Midi; // might noe be vec type

Dynamic Arpeggiation

Arpeggiate notes with changing patterns based on velocity or time.

fn dynamic_arpeggiate(self: @midi, base_pattern: ArpPattern, dynamics: VelocityCurve)

[baitcode]

May I try my hand at this?