key argument

[tlevine]

I want my music to have a key so that it sounds decent. There should be a key argument for to_midi that acts like this.

key=A4 or key=440: The mean value for each column will be middle A, and the key of A major will be used. Data will be scaled so an octave up (A5 or 880) is a standard deviation above the mean.

[tlevine]

We can use the key signature meta-event to store part of this. We'll also need to store the spread and centrality measures, though. We could maybe use a text meta-event.