allow programmatic selection of the drum kit

[santolucito]

The drum kit selection should be something we can control through the code.

[santolucito]

works with b.kitIndex =

should generate this code when selecting a kit through the interface.

probably need to insert synthesis code here: https://github.com/Barnard-PL-Labs/SequencerLiveCoding/blob/e63429a562506f5caf73ad0c1b98e37e4c0b0bfe/public/js/handlers.js#L187

likely need code similiar to this: https://github.com/Barnard-PL-Labs/SequencerLiveCoding/blob/e63429a562506f5caf73ad0c1b98e37e4c0b0bfe/public/js/synthesis.js#L73

called synthKitCode. Should be called in the same way the above code is called here: https://github.com/Barnard-PL-Labs/SequencerLiveCoding/blob/e63429a562506f5caf73ad0c1b98e37e4c0b0bfe/public/js/handlers.js#L90